PC won't start after sleep mode, urgent.

[neon4]

Hello, I have an urgent problem with my PC
Yesterday I put it into sleep mode and today it won't start. It has never happened before.
The LED flashes signalising it is in a sleep mode but nothing wakes the PC up.
I tried:
- ctrl-alt-del to turn it on, but no effect
- using anything to turn it on, keyboard, mouse, the power button, reset button, no effect
- holding the power button has no effect
- switching off/on the PSU no effect
- switching off the PSU, removing/reinsterting power supply cable, switching on the PSU - no effect

Even after I remove the power cable or switch off and on the PSU, the LED still indicates that the PC is in sleep mode! And nothing responds, no buttons, nothing.
I've tried to turn it on only with the vital HW needed to make it run, still no effect, only LED flashing.
When I plug in keyboard, mouse, monitor they flash like normally when it gets plugged in into a working system, so I think the PSU is not the problem, but I'm just guessing.

If anyone has any idea, please help, I'm lost.

 

[DaronMal]

Have you made recent hardware changes to your computer? Check all the wires inside the case to make sure nothings loose? I really could tell you what might cause it, if you have an extra hard drive, try to boot up Windows on the other one.

 

[neon4]

No I haven't changed anything, It's been a month since I even opened the case.
I tried booting the system from my laptop's HDD but it has no effect, still only the LED is flashing like it would be in sleep mode.

 

[IsaacC]

I take it you have already done this, but on almost all systems if you hold down the power button for a solid 5 seconds it should do a override power down style thing, try that and see if ya get any luck :3

 

[DaronMal]

Can you do anything at all? You've tested your keyboard/mouse to make sure they're working? My only idea that might help is to boot up from Windows install CD and try to repair it, if not, you might have to just fresh install Windows, which means lose everything.

 

[neon4]

@IsaacC
I tried that, I stated it above already
@DaronMal
I can't get to run the whole system, it just doesn't react, my accessories seem to be working.

UPDATE:
I managed to run the system, only CPU and RAM plugged into the system. So my guess is that the HDD is corrupted or windows on it, but then I don't know why I couldn't boot from my laptop's HDD either....

 

[DaronMal]

Maybe your mobo is having issues? I'd try to backup your hard drive ASAP

 

[neon4]

Ok I managed to repair the PC, I don't know what caused it, but here is what I did and what I think fixed it.
- unplugged everything from the motherboard, including power supply cables
- plugged the power cables into the motherboard
- short-circuit the power-on pins (turn on the motherboard with CPU and RAM only by not using the power on button, which uses the little cables - wtf)
And voila it worked, then I just put it all back together and everything is fine.

Thank you everyone for your input and your help!

 

[primewaydesign]

Ok I managed to repair the PC, I don't know what caused it, but here is what I did and what I think fixed it.
- unplugged everything from the motherboard, including power supply cables
- plugged the power cables into the motherboard
- short-circuit the power-on pins (turn on the motherboard with CPU and RAM only by not using the power on button, which uses the little cables - wtf)
And voila it worked, then I just put it all back together and everything is fine.

Thank you everyone for your input and your help!

This worked for me perfectly. Thanks OP!
This had nothing to do with the hard drives!

In addition to that:

Remove all RAM cards
Remove the power cord
Replace all RAM cards
Press the power button to clear all power in the machine
Replace the power cord and all RAM
Start up the computer (you'll receive error message)
Shutdown again (also remove the power cord)
Replace all the component back to the machine.
Start again (now everything should work, hopefully!)