I can't join my server.

So, I recently changed my username, and I can't go onto my server because it can't 'verify my username'
Is there a way to be able to have it work? It might've been asked already, but I'm still somewhat new to this.
I don't know if it has anything to do with my username change??
I just wanted to see if there was a way to fix it;
I was thinking of trying to change the online mode and then change it back to what it was before, but I wanted to see if you guys could help somewhat. Any help is appreciated! ^^'board.aternos.org/wcf/attachment/498/

It's working now! Thank you both for your help!!
I appreciate it.