Monitor not working! [RESOLVED]

I have a computer that I just fixed. There was a virus in the start up so I shut off all the start items and restarted the computer. When the computer turned back on everything was fine. I left the computer alone in the room with my friends dad, he turned it off to put the cover back on and when he turned the computer back on the monitor wouldn't work at all!

The monitor still works on other computers but his, I tried changing the video card and it still wouldn't work, not even the start up screen will show, abosolutly nothing comes on the screen.

Please help me!

do other moniters work with it? does it beep?

no the others don't either. I have tried three, I even changed the video card and still no luck.

The computer still turns on and everything but the monitor dosn't work.

I have expirenced the same problem with the custom computer I built, and took it all apart and put it back together again then the monitor worked but I still didn't figure out the problem.

...:::ONE:::...

check the ram! take all of it out and try with a different one (if you have a different one), or try one piece at a time.

I thought that might be the problem but I didn't try it, I think there are two sticks one is old and the other is new is it possible that are bad? Should I test each one to see which one os bad?

Did you check the BIOS Setup screen? Maybe there's an onboard graphics adapter that is enabled? Does the computer beep more than once when you boot up?

Nothing comes up on the screen at all so I can't even see the BIOS settings if I wanted to. The monitors act as if they were not pluged in at all.

I tried changing the video cards, so I think it could be the RAM. I don't rember how many times it beeped, I'm not at home right now so I don't know how things are going to work.

...:::ONE:::..

try taking out the CMOS battery. If you have an onboard vid card that will take over...it will be an easy way to see if the video card is shot

If there's onboard video, there would be a plug for it. If it beeps more than once, then there is a problem. I'm thinking that the old and new ram are not compatible with each other. I had the same problem. A system stopped working an hour after I left. It turned out to be the wrong speed ram.

i would say 4 out of 5 times the problem when there is nothing on the screen it is either the wrong ram/bad ram/no ram/ or ram is inserted incorrectly...

especially if it looks like the video card is not getting a signal

Thanks guys for the help, I will test the battery and take the old ram out and use the new one instead, I sure it will work as soon as I get home from vacation I will check.

...:::ONE:::...

The virus probably eliminated the monitor driver and prevented a new one from being automatically installed. Try using another harddrive with Windows already installed as a test to see if it'll load up. Also be sure to remove the one that's currently in there as a precaution.

no, I switched the RAM and it started working again.