I finished a roll of film in my OM2 this afternoon and loaded a new one. After loading I wound on from the start mark to check that it was winding on correctly and then closed the back. The shutter fired as it should. But after I wound on to the second mark, the shutter release and the wind on lever seem to be locked.
The mirror is not locked up and the check/reset indicate that the batteries are not low.
make sure the camera is on, that the batteries really are good, that the shutter is not locked.
all else fails, rewind the film enough to release it from the take-up spool but NOT enough to wind the leader into the can, open camera, take film out, try winding and cocking again.
I reckon I heard the rewind button reset itself and thought that the film has wound on when it hadn't. I've just tried a multiple exposure and it's freed things up. The film has now advanced to frame 1 ready for tomorrow.
Don't think this would do it, however you might try pushing the little reset button at the base of the place where the lens mounts while also moving the shutter speed ring. Don't have one in front of me and it isn't going to screw it up. Bill Barber