Hi ,Thanks for your reply.
I was unable to do system restore through normal mode.
Then i later restarted the system inserting Win7 dvd, pressing F8 it went to safe mode.
Did system repair and was not successful ,finally did a system restore and restarted the system it said was not successful.
But after that i was able to access all the file i.e.regedit.exe, gpedit.exe, exe.files or word or ppt. etc.
First thing I turned on UAC.