The question is not if you can replace it, but whether it is in fact broken or you have a persistent overcurrent (or other condition) that is keeping it tripped. These things in the panel are not "switches" but circuit breakers.

The condition of the bar onto which the breaker is mounted needs to be properly evaluated. The breaker may have worked loose and over time, the bar has become burned, perhaps even ruined.

Make sure you have moved the breaker completely to its off position before trying to turn it on. This may require some force. Not enough to break the handle of course. If you just try to turn it on, it will not "catch" and the handle will simply feel loose.

If you have other free slots in the panel, you may just want to get a new breaker and install in the free slot. Of course, the free slot would have to be located where the existing branch circuit wiring can reach.

"I have never done any electrical work, but from what I'm reading replacing a single breaker box switch looks pretty simple as long as you make sure it is getting no power. "

The issue with working in main panels (especially) is that even with the main breaker for the panel off, the lugs and lines from the POCO to the panel are not just hot, but have VERY large currents behind them.

A short to ground or across them is as likely to melt and destroy the shorting object as anything else.

Even up to thing like 1/2 inch screwdriver shafts.

It is NOT a good place for an inexperienced person to start.

If it is a sub-panel you should be able to kill the entire panel from its feed source.

It is clear from your post where you call a breaker a switch that you should go nowhere near your main breaker box. You could very easily electrocute yourself. Hire a licensed electrician. He/she will determine if you have a circuit with a problem, or just a bad breaker.

I'm not being rude, I'm being honest.

It's quite easy, but as the other posts warned, there is a danger. Breakers do have a rated life and do go bad. If you feel that you can do this, the first step is to obtain a replacement circuit breaker. Lowe's or Menard's carry most brands. You will need to remove the bad breaker and take it with you to ensure you get an exact replacement. Here's how to do it.

First turn off your main breaker.
(Have a flashlight handy as all of the power in the house will be cut.)

Remove the the panelbox cover (usually 4-screws using a flat-bladed screwdriver). Then remove the broken circuit breaker. Breakers are stab-locked to the bus bar. To remove it, use a flat screwdriver and pry the breaker from the side nearest the middle, (where this breaker buts up to an adjacent breaker across from it). It will pry up as if it's hinged at its base (where the wire connects.)

Once out, disconnect the wire using a flat-bladed screwdriver. It will be black-colored wire. Fold the wire back out of the box (it's dead, no harm of sparking or getting a shock).

At this point I would replace the cover using only one or two screws, taking care not to pinch the loose wire. The idea is to provide some protection while your at the store. Turn the main back on and tell your wife to keep everyone away while your gone.

Once you back home with the new breaker (which should be less than $10), you just reverse the process. Turn off main breaker, remove the cover, attach the wire in the same manner it was attached to the old breaker. Make certain it's tightened down properly. Nice and really tight.

You install the breaker by setting the back of the breaker (where the wire is attached) to its connection point and then rotate the other end down onto the bus. Look a the surrounding breakers and you will see how they are attached.

Just as the breaker is about to be seated, there will be a small amount of resistance. You continue to push through this to get it firmly seated. Once this is done, just reinstall the cover and turn the main back on. (Remember to go around the house and reset all the clocks.)

One last thing. This is the most important part. Even though the main breaker is turned off, there is still power in the box. 240 volts and up to 200 amps.

At the top of the main breaker are two large wires. This is the service entrance feed from the transformer out on the pole. These two wires are ALWAYS hot. Always keep this in mind if you try this and remove the cover. Stay away from the main breaker when the cover is removed.

Turning off the main kills all power throughout the box. But those two terminals on the main breaker will remain hot; and extremely dangerous.

If you decide to get an electrician to do this for you, I would imagine he would charge about $60/hr and perhaps $20-$30 for the breaker.

"To remove it, use a flat screwdriver and pry the breaker from the side nearest the middle,"

It should swing out with only hand pressure (thumb actually) on the handle.

They are rarely that tight in a residential box.

If you have no basic knowledge about electrics or no experience at all fixing such things I suggest never attempt to do it yourself instead call a professional to fix it for you, much better to spend some bucks than endangering your life.

Here is a link that might be useful: Woertz

I have the same problem with schneider breakers (this http://hardware.eu/breaker/schneider/lv429640.html) and I have too replace it. I think you need to do it anyway. And better call master if you are not sure you know what to do.