You can recovery a stolen account on Steemit by heading over to

https://steemit.com/recover_account_step_1

If you have your steem stored in Steem power. You should still have 1 week of "grace period".

As always, be smart about things, think like a hacker (if I'm a hacker, would I do this?) when making any decision online, especially involving cryptocurrency.

People are always trying to yank cryptocurrency away from weak hands. Dont be that weak hand.