my computer wont boot up?

Is it correctly plugged?
Any beep sequence? It sound like what?
Any unusual num lock, caps lock scroll lock led code? It looks like what?
If any thing appears on the screen, what do you see? When does it stop?
Can you enter the BIOS setup?
Is there a power supply?
Is there any RAM?
Is there a CPU?
Is there any hard drive?
Is there a disk in the CD or DVD drive? Try removing it.
Did you try any thing to correct the problem? If so, what did you try?

Without any description of any symptoms, nobody can help you. In some cases, the brand and model can be useful.

Electro
March 2013