Account Hacked?

well this morning when i went to go play some black ops i turned on my xbox and saw that the only account i could log into was Leet Venusaur, from when he was at my house last month, i was like wtf wheres blastoise?! so i went to recover the gamertag which i thought would work but then after trying all the right information i get a message that says account is not valid, after research via forums it said that basically someone tried recovering it on their console, but then stopped halfway through, and i cant recover it back to mine, cuz its "unrecoverable." its not on anyones xbox atm, just out in internet space, and idk what to do so im prolly just gonna make a new gamertag, seeing as how leet blastoise just ran out of time today.