Are you saying when you switch the computer on there is no audible beep from the tower?
Is there a solid LED light on the front of the tower once you press the start button?
Is there a second LED light that flashes on and off intermittently?
Can you hear the fans start up?
Do you feel air coming from the rear of the tower nearer the top?

Restart your computer.
When the machine first starts again it will generally list some equipment that is installed in your machine, amount of memory, hard drives installed etc. At this point you should gently tap the F8 key repeatedly until you are presented with a Windows Advanced Options menu.
Select the option for Safe Mode using the arrow keys.
Then press enter on your keyboard to boot into Safe Mode.
Let us know if you can get this far.

LOTS of helpers willing here, answer owbists' questions. Probably better to know that information first.

The solid blue light stay lit on the tower it does not flash on and off there are no beeps from the tower the fan works I feel the air. The keyboard does not work or the mouse I have tried hitting the f8 key nothing the monitor just flashes once that it is in power saving mode then goes black screen and the light on the monitor turns amber. Thanks for getting back to me.

The solid LED indicates power. The lack of a second, flashing LED indicates no signal is reaching the hard drive or the hard drive is dead. I doubt very much there is a problem with the hard drive, likely more serious as there is no BIOS beep.

Have you noticed the time or date refuse to keep the correct time lately? If so remove the power cord from the back of your tower. Remove the left side of the tower, lay the case down on the other side. Look at the motherboard and find a round shiny disk about the size of a quarter, this is the battery. You should see written on it CR2032. Looks like {{gwi:1456975}}.

Remove that battery keeping your bare hand or arm resting on the metal of the tower to dissipate any static electricity from your body. Now rub both sides of the battery to clean it and replace it in the computer, again keeping bare skin touching the metal case.

Reconnect the power cord and try rebooting. We'll all keep our fingers crossed at this point.

If you have never been inside before just take your time and everything will be just dandy.

I took the battery out dusted it off put it back in still isn't working. I don't remember the clock being off time didn't notice really. Do you think it could be a video card? I'm not sure how to check that out. thanks again for helping me

It could be anything at this point. I don't think you have a video problem though. The reason for the black screen is something else I would guess. Like Ram, Hard drive, power supply or even mother board \ Processor. It's a difficult issue to resolve from here. I would start with ram. That's about all you can do really. Some would suggest pull the Video card out then try to boot to safe mode see what happens.

So if there are 2 sticks of ram pull one out and start the computer an see.

That's all I recommend for now.

You"dusted" the battery off? I hope that means a vigorous wipe especially on the underside to ensure a good electrical connection.

This is not the video card your POST (power on self test) did not complete, if it started at all that is why there is no beep. A bad sign. Removing the battery as you did also resets the BIOS to default settings so they are fine for what we need.

At the best your power supply has failed on the lower voltage leg/s at worst your motherboard is toast.

Take another look inside and tell us the make and model of the power supply please. Also tell us what peripherals have been connected to this computer via USB or Firewire ports.

Actually I just went searching, it seems you may have a Bestec power supply and they have a terrible track record. On many eMachines the power supply would fail and take the motherboard with it making the whole thing garbage. You might consider visiting a local repair shop and see if you can invest $10 or $15 on a used power supply and hope your motherboard is still good.

You might give us a model number too so we know for sure what we are dealing with.

I took the battery out and really rubbed it put it back in and hit the F8 key 3 lights flashed on the keyboard then just one stays lit. Printer is on dvd slots open and close. Monitor is still black screen no mouse.
Battery-cr2032 newsun 3v
USB ports
linksys wireless-G2.4 GHZ broadband router
Printer-HP psc 2110 all in one
This is a Gateway 7200x
Thanks again for helping me

have you tried unplugging the monitor from the pc, wait a few secs then plugging it back in? are there button on your monitor if so try hitting the auto adjust button. Do you have another monitor you could borrow or use to see if things are working that way?

We're progressing - slightly - but any gain is good hopefully. Did you hear a single beep? Before these troubles did you hear the beep within a few seconds of starting the computer? Right now the beep might be the most important clue of all

The power supply is the metal box usually in the top back of the case with all the wires coming from it. On the side facing you as the left side panel is removed from the case will be the make an model please.

Remove the power cord from the rear of tower for the next bits.

Check underneath the fan located on the motherboard and more importantly the cooling fins underneath. Are they clean, reasonably clean or clogged up? If the fan and cooling fins are plugged with crud it needs to be cleaned, the computer will quit automatically to protect the CPU if sufficient air cannot circulate. (Sorry, this should have been asked in my first response)

Remove the memory stick/s and start the computer, you should get constant beeps. Shut down again and let us know. This will help decide if the motherboard is dead or not. Look at {{gwi:1456976}} link if unsure what memory looks like. One or 2 sticks will be in slots similar to those 2 long blue and long black slots all close together on the lower left side.

The computer worked fine I heard the normal beep on starup then load up and the next day nothing. Me and my husband took the memory cards out one at a time and would turn on the computer nothing except when both were out we got 3 beeps we put then back in nothing. there is no dust it has been cleaned. We took out the video card got nothing even moved the monitor wire down to the onboard video still got nothing. We put a new power battery (little round one)still nothing. We cleaned the power supply we took it out and cleaned it didn't disconnect anything we were very careful with it. still nothing both fans work. We took it to a geek guy today at best buy and he put a video card in it and did a few checks and said it was the mother board and told us that we could do this ourselves so cross fingers and toes. But you wanted my power supply # it is model# hp-p3087F3. Again I can't thank you enough for helping me.

Do any of the capacitors on the motherboard look like these by chance? (Bulging and/or leaking tops). If so, yes, the board is essentially done.
news.cnet.com/i/ne/p/photo/capacitors_apple_500x375.jpg

We took it to a geek guy today at best buy and he put a video card in it and did a few checks and said it was the mother board and told us that we could do this ourselves

Did he tell you what to fix or how to fix or what was wrong on the motherboard? If so were you able to do as he suggested? I find it odd he would say how simple it was yet never fixed it, he obviously made a charge for the work he did do.

The 3 beeps with no memory is positive news. We know the motherboard is receiving power now and that the memory is good. We know the 12 volt leg seems good, at least from the motherboard to the CPU and case fan.

I didn't do anything yet I did check the capacitors and they do not look bad. I don't know what else I can check or how. I am at wits end that is why I went to the geek kid he was really nice and he didn't charge me he told me if they did the work it would really cost me. I'm at your mercy. Again thanks so much for any help or ideas.

Basically there is nothing physically on the motherboard the average user can fix. The fact that you had the 3 beeps after removing the memory almost confirms that the power supply is good.

You could remove the power cord from the back of the case then remove each electrical connector on the motherboard 2 or 3 times to rub any crud or corrosive deposit that may be causing power stoppage but it is a long shot. (Remember you had to do that in the old days of early remotes for the TV? Because the channel selector never got used it would tend to gum up so you could crank the knob around 3 or 4 times to clean it off. That cost me $39 once.)

I wish myself or someone else could offer something positive. If you sink money into this machine it is still a 6 year old computer which in the electronics world gets viewed as quite old. Repair costs can be prohibitive and that could well be a good part of the price of a new and faster machine with a year's warranty.

Thanks again for helping me but my husband thinks putting in a new motherboard is going to be soooo easy and plug everything back in and like magic it works and I told him I think it is going to be a little harder than that and I don't know much about computers so if we do this you just might see me back in here looking for help. Again I am so grateful for your help.

Some information. See link in case anything was missed. It's actually a good trouble shooting guide.

Remember replacing the motherboard will not include Ram or the processor these Items could be at fault.

Here is a link that might be useful: -gateway-7200x

Your husband may well be able to rebuild this computer. However it would be best to ensure that the issue is with the motherboard and not some other component. What if you buy the board for $100 after being absolutely sure it is the same and all the current components are compatible but the computer still does not work. Returning good parts is not an accepted way with computer stores. The chances of finding a 6 year old motherboard are slim at best, current boards will not accept those older parts probably. Somewhere on that board is a model number and revision number to make the search easier.

Most importantly you cannot use your current XP operating system so you need to buy another one, another $100 plus gone and for an operating system 2 steps behind the times. Your current XP is tied to the specific motherboard it was installed on with factory built computers.

You will need to ensure you either have all the CDs that came with the computer so that all the drivers are available or that you can find them for free online.

The processor will need cleaning once removed and it will require Arctic Silver or equal quality paste to re-seat the heatsink on the processor. This bit is the most difficult or frightening apart from deciding on what parts are compatible.

Do the math then take a look at today's computers for pricing. Also if hubby feels good about it check components to self build, it can be a very gratifying experience once all the parts are determined and compatible with each other. You likely will only be able to salvage the hard drive from the existing machine if you build new.

Just an update to my problem I bought a new motherboard(39.00)from skyline eng. same exact one that was in the computer we put it in I went on line and read how to remove a motherboard and how to put in a motherboard and the processor(it is the same old one) and we are ok now computer is working. Thanks all for helping me.