This question already has an answer here:
A friend of mine fell victim to a mailbox hijacker the other day, and Gmail helped her recover the inbox (via whatever method they do so, I was not present for that). I showed her how to recover her contacts (that has a handy recovery menu option) but she's missing data for about a week of email. It's not "hidden" in a filter, it's not "in the deleted bin".
Is there any way to get all of that emails back?