No Idea What I've Done To My PC

So I was trying to uninstall Ubuntu, and put the partition back into my C drive, because I've been desperately low on space. One of the guides I read, said that instead of using a recovery disk to access the command prompt in the system restore, I could use Hiren's Boot CD. To test this, I booted from the CD, and in the CD options, chose to boot my Windows OS. As soon as I logged on, I was met with a black screen, with a message in the bottom right corner saying "Windows 7, Build 7600, This copy of Windows is not genuine." So I tried to do a recovery, but it told me I couldn't because I didn't have space on my C drive (which is why I was trying to uninstall Ubuntu in the first place). Booted into Ubuntu, deleted a couple of things (none of which would have messed with Windows). Tried to boot into Windows and was met with ridiculously long load times into safe mode, recovery mode, and normal, all of which froze. Now it won't even get past BIOS.

I have a friend who thinks it's a virus, but I have no idea, and no clue what to do if it is a virus, because I can't get into my OS to run anything.

HELP!!!

Not a virus, just the boot is messed up.

At this stage I would reinstall Windows from scratch, or take it to a computer shop to see if they can fix the boot.

format c: /s

This.

Insert CD, boot from CD, format your OS partition, install clean Windows.

if you have important data on that drive that you cannot lose, you should try sticking that drive into another pc or booting from another drive in the same pc, backing up your data and then doing what the above posters have said.

Did you boot from a Win 7 (preferably made by your install) recovery cd and ran bootrec.exe from the Command Prompt with the following options?

bootrec /fixmbr

bootrec /fixboot

Insert Hiren's Boot CD? Or boot from a recovery CD?

@jun_aka_pekto I never got to that point. Windows started going catywhompass before I could

Windows CD

It should be the appropriate recovery CD created from the same version of your OS, that is, make sure the recovery CD is for Vista or Windows 7 and 32-bit or 64-bit.

You have to set the BIOS to boot from optical drive. It should bypass the hard drive completely. Plus, make sure you keep an eye for the prompt to press any key when the message, "Press any key to boot from CD" appears. Sometimes, that message doesn't last long.

Or... use the OS disc for your installed copy.

Edit:

It should work. I recently deleted an Ubuntu server partition from my Vista PC. I booted from my 32-bit Vista restore disc and ran bootrec with both the /fixmbr and /fixboot options. Worked like a charm.

So I let it sit overnight and it seems to be working fine now. Are there any measures I should take to ensure it doesn't happen again?

Should I go ahead and restore it to a point I made yesterday before I tried uninstalling Ubuntu?

I would try a restore point maybe like a week or month ago before this ever happened. Or just reformat. I am glad its gone, but the issue will return at a really bad time.