If your character gets stuck in a custom map the best way would be to remove the maps from your FH that holds this character(And actually make sure it's the CORRECT map(s)).
Once that's done you might be able to get your character out from a big black room by just resetting your home and going home again. However, if that doesn't help, and you get stuck on a loading screen saying "Failed to connect to map server", and nothing changes within the first hours, you must actually wait for the server to be restarted which it can get sometimes several times in a day, sometimes there's a few days apart.
If your character would for some reason still be stuck after around a week it would just be odd. Patience as mentioned before. Server restarts usually fixes stuck characters depending on what kind of thing you were doing. But do not take this as an guarantee.
In worst case scenario you can always recreate your character of course.