wordpress admin bar missing

SOMEone I met on line !!!! has been trying to customise a few things on my site but he has
A: messed up
B: gone M I A

I cant get hold of him and the main issue I have s when I am logged in and click on my site, the wordpress bar at the top is missing meaning I cant get back in unless I press back and lose updates or log in again every time.

Is there anything I can do plzzzz

Tnx