You might want to use the research (google) "button" at the top of the page and enter some key words there as there are a number of posts about this issue. Your ejector rod may have come loose and is preventing opening the cylinder. If so, you may be able to tighten it enough with thumb/finger pressure to allow the cylinder to open. On the other hand, it may be another issue. I pulled a pre-24 out of the safe last night that I hadn't shot in years and could not open the cylinder. Tried the ejector rod tightening routine but that didn't help. Took the thumb piece off, squirted a little Rem oil in, tightened it back on. . . .and the cylinder opened. Magic, sort of. Good luck.
Jeff
SWCA #1457