my pc is get turn off after i starts restoring my iphone 4 please help

Hello Lakhan Gaikwad,

It sounds like you are trying to restore your phone but in the middle of the restore, the computer is shutting down unexpectedly. I recommend starting by trying the steps in the following article first:

Resolve iOS update and restore errors in iTunes

http://support.apple.com/kb/ts1275

If the issue persists, try checking to see if any 3rd party plugins are installed, that could be causing the issue:

iTunes: Troubleshooting issues with third-party iTunes plug-ins

http://support.apple.com/kb/ts3430

If it is still unresolved, what version of Windows is your PC running?

Thank you for using Apple Support Communities.

All the very best,

Sterling