Bulb blew last night. Trying desperately to get it out to change bulb but not budging. Got the outer case off but the end covers aren't budging so bulb won't pull or twist out.
I've seen some units where the bulb wasn't designed to be replaced. Based on your photo, that may be the case here. Units with replaceable fluorescent bulbs have a "twist-in" connector on either end that's visible after you remove the cover. You may need to buy a new unit and replace the fixture. I would buy a double bulb unit, since those are almost always replaceable.
It had clips on the inside of the cover. Managed to get a screwdriver underneath which freed the clips and then would slide off.
Not all fixtures twist some are spring loaded where you apply a light force to one end of the lamp. The spring collapses and the other end will drop out. This kind of fixture is mostly used on single pin tubes but I have seen them on standard lamps also.
Put on safety glasses when you try to remove it. I just broke a circular bulb trying to remove it. It was held by very stiff clips.
My fluorescent tube just would not turn to get it out. I took 2 strips of duct tape and layed them over the bulb near both ends. Couldn't get it around the tube all the way. I then pulled on the duct tape which had a pretty good hold and the tube twisted allowing me to change the fixture.