Can I fix my fn volume with out a download

Hello,

I was playing with my 18 month old cousin when he walked over to my laptop and pressed a few keys together like the ctrl, fn, alt, and the start menu keys in the lower left keyboard. He didn't pound them real hard or anything, he just pressed them. About 20 mins later I noticed that the volume keys were not working. I tested the brightness functions to make sure the fn key works. Those are really the only 2 functions I use the fn key for. The only keys not working is the Volume. Did my cousin turn it off? Is there a way I can get it working again with out having to download a program?