i recently left my computer on while i was at work and when i returned it had shut down, thinking that it had just gone to sleep i pressed the power button and it came back on, that is all the hardware, monitor, hard drive, video card, fans, and led's came on. but it didn't beep signaling the start up. does anyone know why this would happen? all my components have power and the computer worked 2 days ago just fine. if anyone has any ideas please let me know. thanks.

What is displayed on the screen at power up? You haven't said - you only mentioned the beep.

Does the keyboard flash?

now i have no idea what can be wrong. the monitor doesn't display anything, just a stand by light. the monitor works with a laptop output. the keyboard doesnt have any lights on, but the wireless reciever for my keyboard and mouse has power

What would I do? In your described circumstances I would put the HDD onto another PC (in a USB enclosure which is a must rather than slaving it) and would run diagnostics on the disk.

If you are still following this thread then I should let you know that its either your MOTHERBOARD or your VIDEOCARD that has gone KAPUT !! From what I can understand you probably don't have a tester, so I would suggest, take your CPU to a hardware store and ask them to check your Motherboard and then your Videocard. The BEEP AT THE START means all hardware is working properly. In your case its not. Replace the Videocard or motherboard or both depending on the result and you should be right. Let me know if you have any more questions