I think someone changed my password

I think someone has hacked/changed my password because I have my password saved into firefox and when I try to log in it says it's invalid. It was working a few days ago and I havn't changed my password. I can't recover it from email either because I gave that email ([email protected]) to a younger sibling who has passed away. The email I now use and have been using for sales on here is [email protected]. I would really like to sell some more stuff ( I got a new stock of CD keys ) and I can't unless I use this account because of vouches.