computer dead please help

[Luis Ortega]

I have a windows 7 computer that has run fine for a couple of years.
I was away for a month and left my computer off and after I returned, it worked fine for a few days and then I got a series of blue screen crashes. Then it failed to even turn on.
You can see a power led lit on the motherboard before it is turned on but when I turn it on it won't show anything on the monitor, it makes no beeping sounds at all, and after a little while, it seems to restart itself and try again but I get nothing at all on the monitor and it won't go into the bios setup or anything.
I took it apart, cleaned everything and reseated the ram and all connections, but it refuses to turn on or show anything on the monitor.
I tried putting the ram in one stick at a time and in different slots, but it made no difference. I hooked up the hard drives to another computer but they seem fine and I can read and copy stuff.

Can anyone please advise on which components may be causing this?
The motherboard? The ram? The cpu? The graphics card? The psu? Something else?
I do not have a second computer to try swapping components around to see which work.
Thanks for any advice.

 

[cammykool]

Do you hear the windows login chime?

 

[Luis Ortega]

Do you hear the windows login chime?

Thanks for answering.
No, there is no sound or anything that shows up on the monitor.
The computer seems to get power, the fans go on on the case and the graphics card, but there is no bios logo or post screen or sounds or anything, then after a little while, the computer seems to try to reboot, the fans restart but nothing happens.