windows 7 doesn't start

Please help!
I have Windows 7 ultimate x64 and my computer has been acting strange lately till yesterday when the computer starts and the Windows 7 starting screen appears it shuts off and restarts in recovery mode so when I try to repair it so it asks me to select an operating system but there's no operating system It's just blank, even more strange when I put in the windows 7 dvd and I try atleast to install a fresh copy it wouldn't recognize my hard drive, what can I do? Is it a virus?
Any help would be greatly appreciated.

Test your HD using maker's diagnostics/repair Extended CD scan: HD Diagnostic

If HD is OK see if you can boot into Safe Mode with Networking to install, update and run Malwarebytes.

If no Safe Mode, download, write to flash stick or burn to CD, boot to run a full scan with Microsoft Standalone System Sweeper.

You'll then know if you've been infected. Run scans repeatedly until no more infection exists.

If Win7 still won't start boot into DVD Repair console to run Startup Repair repeatedly.

If no installation shows to repair, try to jumpstart it by opening Command Prompt from Repair Options list to run:
bootrec /fixboot
bootrec /fixmbr
bootrec /rebuildbcd
Then see if an installation shows to repair, or run Startup Repair repeatedly anyway, report back.

I was about to follow these instructions but now when I power on my computer the screen just won't turn on and I tried a different screen what do I do now I'm screwed

Are you getting any error message on screen, flashing cursor, anything other than a black blank screen during the entire startup on both monitors tried?

Are the fans spinning in the case? Which LED lights are on?

My computer has only one led and it works, the fan of the power supply works how do I know if the CPU is working