Why can't i start my computer?

whenever i open my computer it shows me some options on the black screen. The options were: safe mode safe mode with networking, safe mode with command prompt , last good known configuration and start windows normally. I tried all of them but my computer just restarts. So i went to the advance menu with Directory services restore mode, Debugging mode ,Disable automatic restart on system failure, etc. Nothing work's.Somebody please help me!