What to do if Windows 7 won't start?

Question

Keyboard

I can't start my computer. "windows error recovery" is displayed,
"Start recovery at startup (recommended)" is automatically selected.
After 30 seconds, the entry "downloading files" appears and again "windows error recovery". Then again, after 30 seconds, just a black screen appears, after 10-20 "windows error recovery".
And the MOST STUPID, I can neither choose normal boot nor press f8, as they say on the sites, since the keyboard does not work exactly when this very "windows error recovery" appears !!!
What to do???

Answer 1

No matter how trite it may sound, but most often in such cases it is easiest (and faster, if you have more or less direct hands) to reinstall Windows cleanly (with formatting the system partition), after booting from LiveCD (USB) and saving (moving) the necessary data to another partition/drive.