Sorry you got hacked buddy but I don't understand how signing post can recover stolen accounts.
When you sign a address it shows that you are the one signing it. It verifys the ip address its coming from.
let's say an hacker steals an account of someone who does that.
If he is a good hacker(or smart and not a script kiddie) he will just copycat your older posts. Lets say from now on I sign my post with F.E.
And I get hacked, but the hacker will just take couple of minutes to study your old posts and copy that. So, an hacker would just copy the fact you sign your posts.