Program fonts screwed up

I was having hardware issues with my Macbook so I took it to our computer help desk at school where they verified it was my ethernet plug and they couldnt do anything about it. I left it there over night so they could screw with it and try to figure it out. I got it back and the next day i realized that my itunes font was real screwed up. The more I looked at it the more I realized it was actually another font I have in my computer that is next to impossible to read when it is in program font. Then after using more and more programs over the course of the past few weeks I realized its not just itunes but also microsoft word, excel, Vuze (bit torrent), my dvd player, and some other random things. I looked into it and realized there isnt actually a way you can change that stuff without a third party program, and seeing how mine was changed and I can't use half of my programs I decided to get Tinker Tool to change my system program font back. Well they were all set as usual and i even changed them with minor changes (IE lucida to Times, etc.) and that did nothing. I have no clue who or what changed my these fonts but I have called apple support and they had no clue how to change it. Any advice would be greatly appreciated.
Thanks!
~Casey