Hi Girish,
The issue description seems a bit unclear and I would like to have a better understanding before we start working on it.
I appreciate if you could help me with more information.
1.
Are you unable to boot into safe mode? Do you receive any error message/code?
2.
What happens when you press f8 button?
3.
Are you able to boot to the desktop?
There are few instances where it took people some time to get to the safe mode, some pressed F8 too slowly, too fast, permanently or too late
but eventually all succeeded. Try using on external keyboard. If you are unable to boot to desktop, I would suggest you to perform a startup repair and check if it makes any difference.
Startup Repair: frequently asked questions
http://Windows.microsoft.com/en-us/Windows7/Startup-Repair-frequently-asked-questions
What are the system recovery options in Windows 7?
http://Windows.microsoft.com/en-us/Windows7/What-are-the-system-recovery-options-in-Windows-7
In addition, you can do a
System Restore from
Windows Recovery Console.
Reply with more information to help you better.