Technical Back from Bootcamp

Recently returning from bootcamp in San Diego, I have come to find out that my account had been stolen. Not too sure how he was able to switch my gmail to his but I do in fact have the gmail name... Anyone know a process I can go about this (with proper proof: debit card, activity, date of account creation 4/28/2010) to get my account back? Hoped I'd be able to play a little more before getting deployed overseas, and would really not like to have to restart all over.