My laptop wont load on to sign in page and keeps coing up with start normaly but

[Guest]

my lap top wontgo on to sign in page and keeps restartin its self

 

[nhasian]

Here are detailed step by step instructions with pictures:

How Do I Use the Windows System Restore Utility?
How Do I Perform a Startup Repair or Repair Installation of Windows?
How Do I Perform a Clean Installation of Windows?

Also there is SFC How to use the System File Checker tool to troubleshoot missing or corrupted system files on Windows Vista or on Windows 7