Unfortunately, you've given us no information about your computer.. Operating system? Brand name? Any and all EXACT errors you're seeing? What exactly did it do when it "crashed"?

Have you tried starting the computer into Safe Mode? If you can, you should be able to backup those important files. (Why didn't you back them up previously?)

How To Start In 'Safe Mode'

Do you have a Netgear wireless adapter on your computer? Any other Netgear components? Router maybe? What type of internet connection do you have and is it working?

Have you recently done any virus or spyware scans? If not, please do.

The more information you give us, the better informed our answer will be.

Hope this helps.