Hello I was wondering  if I lost my old xbox gamer tag and can't recover it but have all my bdo sign in info and proof of micro transactions if pearl abyss can transfer to my new gamer tag

Greetings DrowzyBudz!

Regarding your question about account data being transferred from one gamertag to another.

It saddens me to inform you that this process is not possible as account data is tied to the platforms account, this information can not be changed as we do not manage platform data.

I do not think Microsoft will be able to transfer the account data either but you could reach out to them & alert them that your account has been comprimised & they will provide you the steps to reclaim access to your account.

Xbox Support