Video/Graphics Card

One other thing, the mouse and the keyboard's (green) lights do not turn on either.

Easiest way to find the video card if you know nothing about PC components: Find the thick non-power cable that connects the monitor to the back of the tower. It's either a VGA cable or a DVI cable--both thick with big connectors. Usually the connectors are blue or white. If the cable plugs into your motherboard at a plug with a screen symbol, then you have onboard or integrated graphics and you should get the motherboard looked at (and likely replaced).
If the cable leads to a separate card that plugs into the motherboard, then you have a dedicated video card. If you're getting nothing at all on the screen, this part probably needs to be replaced.
It could also be that the monitor stopped functioning--you can try using it with another computer to be sure.

Also make sure that everything is plugged in and powered--it's odd that your mouse and keyboard don't work.

If you can't easily diagnose the problem then it might be best to call a repair shop or a relative who is more knowledgeable about computers.