Laptop keyboard acting strange

Hello,im mike and i have an ASUS Notebook K40ID/K50ID Series, windows 7. And a couple
of days ago i noticed that some of the keys on the built in keyboard just do not respond to anything.
it is rather annoying having to use the on screen key board all the time. i would really appreciate assistance
i hope this following information helps in some way
the letter keys that do not work are as follows:
w r t y u i o k , 8
than the numlock keys that do not work are:
1 2 * 5 8
other keys that dont work:
Ctrl (start menu key) (left arrow key) Tab PgUp End
Th Fn key only seems to have an affect on activating ScrLK and calculator but nothing really important.

okay thats all.... i think. i would really appreciate assistance on this. thanks