My Xbox account corrupted?

I transfered my Xbox account from my 360 hard drive to my portable drive so that i would be able to play on my friends 360 usimg my account not guest. it worked just fine. but when i connected my portable drive to my 360, it said account currupted. i checked the memory it was there but currupted, i transfered the data to my hardrive but still didnt work. i used the recover gamertag to recover it but wouldn let me log to my account. theres the other problem. i used a yahoo acount to log to xbox live. it let me. but now i cant axcess it it just says error. so i cant recover it using its orriginal email. PLEASE HELP. i worked really hard on it. i played games that werent mine so i cant play them again! i really dont want to start all over. PLEASE HELP.