I moved my tower, disconnecting everything, and when I hooked it back up, there is now a constant beep and the monitor is black. I've checked and rechecked to see if everything is plugged back in right and it is. I unhooked everuthing again, except the power cord and it is still beeping, so it can't be anything plugged in. Please, someone help!

I moved my tower, ...Please, someone help!!

Moving can often lead to components jiggling loose and needing to be removed and reseated. The most common things are add-in adapter cards and memory modules. The motherboard should be completely depowered (power cord unplugged for 30+ seconds) before removing any component. Connecting PS/2 style mouse and keyboard backwards can also lead to beeping with some motherboards.