WINDOWS 7 REPAIRS IN LAPTOP

Respected SIr/Madam,

Could you tell me the solution?
My laptop configuration is as follows,
OS: windows 7
Processor: intel pentium (R) dual core
RAM: 2 GB

My laptop has problems, All programs in start menu has a programs installed in my system. If i open a notepad, the all programs in start menu have been applied to the notepad extension(properties), it likes a ms office , word pad have been changed to note pad properties, and which can not be used.

What can i do for repair that?