Certain Macbook Pro keys not working

Hi,

Some of the keys on my Macbook Pro have stopped working. These keys had stopped working previously in July for about a day before they went back to normal; they have stopped working again and will not start again. This is a list of the keys that do not work:

p

\

enter

;

/

0

lower volume

volume on/off

I have never had any problems with my computer until now. If anyone has any ideas as to why this is happening/how it could be fixed, I would appreciate them greatly; I'm trying to avoid taking my computer to my school's tech people or the Apple store.