Most of my damn gamerscore dissapeared..HOW?!?

here how it happened: well i havent hooked up my xbox to xbox live in a while but when it was offline i played alan wake, mass effect 2, left for dead 2, and enslaved (all good games) but then my thirsty *** cousin comes around and fixes the xbox live and play's for at least 2 days non-stop but today he has to take finals anyways when i go upstairs and decide to play mass effect 2 i notice that 1/4 of my damn gamer score was gone and ALLL the achievements i got from playing those games dissapeared WTF happened i was so pissed i wanted to destroy the whole planet but then i got over it and noticed my thirsty *** cousin's gamer profile was gone and i also noticed my other cousin had retrieved his profile after it was deleted by my thirsty cousin...anyways if your still following this PLEASE give me some advice or an answer so i can know whose *** to beat ;D