Windows 7: problem starting my computer

My computer was working just fine this morning but when i got home today it wont boot windows or really anything. It shows the motherboard or processor wallpaper type thing when it first starts up just like always but after that it goes straight to a black screen with a white flashing bar in the top left hand corner. Its kind of like a command prompt. The only thing i can really do is press ctrl alt delete and that just restarts it. None of the f keys at the top work or anything.

I also have a back up of Windows on an external harddrive but im not sure how to boot windows from that since nothing is loading. The computer is only a few months old and has worked great up untill now.

Thanks

Press the F8 key repeatedly at boot up or use the Startup disk.

Try this:
Safe Mode

Startup Repair
Note: You may need to do startup repair 3 to 4 times.
Startup Repair - Run 3 Separate Times

System Repair Disc - Create
System Recovery Options

The exact same thing happened to me, I'm guessing you have automatic updates? My laptop screwed up after installing updates on 12.1.

Safe mode won't boot up for me, and none of the recovery options work except command prompt. To be precise, I'm getting a "memory 0x00000008 cannot be read" error.

I don't even have a physical copy of Windows since my laptop came with 7 Pro preinstalled...

I pressed f12 repeatedly and it gave me a boot menu. Is there anyway to disable this? I was going to download an auto shutdown/startup for when i wake up and get home from work but im guessing it wont do any good.

Why do you press F12?

Alright i dont know if i have bad luck or what but yesterday i started up my computer and it just sat on the windows loading screen, so after 20 minutes i turned it off (pressed the power button untill it turned off) and i probably shouldnt of done it. Now it just sits on the motherboard screen at the first and nothing works at all. I have pressed every key and still nothing. Is there anyway to fix this?

it gave me a boot menu when i pressed f12

Anyone? im getting desprate here!

Anyways after letting it sit all night and all today untill 12 it finally booted windows (kinda) For almost 8 hours it has been doing a start up repair "searhing for problems" How long does this process usally take?

Note: You may need to do startup repair 3 to 4 times.
Startup Repair - Run 3 Separate Times