do you mean your desktop icons or the icons which are in the taskbar at the bottom of the screen?

if your desktop then right click on the desktop click on arrange icons and select to auto arrange and/or align to grid. If they keep moving around there is a little program you can install that locks them in place so they do not move.
Icon Restore

Don't do a system restore to move icons around or to accomplish other simple tasks. You may lose updated settings that you want to preserve for other features of your computer. As ravencajun points out, there are often simple solutions to problems like this.

well i don't think i explained it right. At bottom left is where the "START" icon should and it's at the top.

You should be able to click on an empty spot on the bar and drag it back to the bottom. Then right click on it and select 'lock taskbar' from the drop down menu and it should stay there.

ok you meant the task bar, click on a clear spot on the bar and make sure it is unlocked(not checked) then as stated grab onto the bar with your mouse hold down on the mouse button and drag the bar back to the bottom or where ever you want it, once it is there again click on a clear spot on the bar and right click to lock it in place. It has to be unlocked before you will be able to drag it from one place to another.
What windows are you using? please always include the info about your system so we can give the appropriate instructions for that Operating system.

To reset your taskbar

on that page you can also just go down to the fix it for me option and do that.