Someone has hacked my Facebook account?

[Dale]

First of all if you can still access your Facebook change your password immediately, then click on settings and click security, click on active sessions and end any that you don't recognise. If you have the same password for your email or anything else change that too.

Tell your friends and tell them to let you know if they see anything.

I'd personally cancel my account and set up a new one, after Facebook gets back to you.