Sounds like a world edit mistake. Your best bet is asking an admin if they were working in that area and caused the error, or having an owner see if they can roll back the damage (I'm sorry to say but this may not be likely if it was world edit, that's why admins need to be very careful when using worldedit in the city...) [Jr.Admins-
@Izzie and
@Auryy and Owners-
@Coban @nibble] Best wishes for you!
Ps: Was there apartments regioned inside the building already? If so, those regions are still there and anyone who rents them now has no home...