Try booting in safe mode, then restore to when it was booting.
Hit F8 key before Windows logo somes up. You should get a screen with one of the options Boot Safe Mode. When it's booted, go to System Restore (in accessories) and choose a restore point that last booted.

This thread is fine, since you have some history of what caused the no booting. But it is always good to start new threads for each issue. It's easier for others to find help when they have similar issues.