I have a flushmount light fixture that I cannot get down in order to change the lightbulb. It is made up of a metal ring with a glass globe held inside the ring. I have tried turning the glass inside the metal ring but it does not budge. I have tried turning the entire unit including the metal ring. It moves a couple of inches but then seems no closer to coming off than before. I have also tried prying it off the ceiling. This does not seem to work either. I don't want to break it but it's not much good to me if I can't change the bulb. Is there anything I'm missing?

It looks like this although I can't say for sure what brand or model it is.

http://www.affordablelamps.com/access-20626-bs.html

Should be several thumbscrews around the metal ring a lip on the glass touches to hold it up, loosen several of those while supporting the glass part.

When you replace it the glass should not hit the screws it should fit loose enough you can rotate it... don't overtighten the screws.

No, there are no thumbscrews. The metal ring and the glass globe are both completely smooth.

The globe may turn one direction or the other.

I've been trying to turn the globe but it does not spin. I don't know whether it is stuck or if it is not supposed to spin.

I am sure it spins, may only turn a quarter turn, counterclockwise. The heating and cooling of the fixture may have caused it to get seized.

Try spray a bit of WD 40 at the seam where the glass and metal meets.