well im new playing halo 3 ,and one day a guy ask me if i want to have all the achivements and a good gamer score of any game i want for 10000 microsoft points and say yes i give him me gamertag and i wait 1 week and he told me whit a message he was already unlinking all the thing i want and he bring me back the account but the problems its i lost all the achivements of halo 3, halo ODST and reach and i dont know why maybe that man was a hacker and hack me all the achivements and keep whit my microsfot points or somethig like that or what o dont know what to do if anyone can bring me a little help couse i play a lot of hours to get that achivements and in a few days i lost everything i have of that games please help me.