lost characters

Hi, I wanted to start playing again after a while. When I logged in, I noticed I'd lost my characters. I'd even made a donation in the past.
Is there any way I could get my characters back?

Are you sure you logged right account and realm? Premium accounts are exempt from cleanup character deletions.

If the realm you played in was Frostmourne (progressive WotLK), those characters are gone.

Character restoration is only available for up to 30 days, if it was done by a player. It's most likely gone by this point, if somebody else had access to your account and deleted everything.