if it has been sitting for any length of time, whatever lube was in or on the gun ,may have coagulated and 'stuck" the parts in place............ put a few drops of kroil or any rusting inhibiting oil, rustbuster, etc and spray the ends of the cylinder, the ejector rod, you coukld pull the hammer back and make sure the cylinder even turns any,yes squirt a bit down on the inside, back of the recoil shield while you are at it....then holding the release in ( down) tap the right side of the cylinder downward on the top of your knee, and it should pop right open............yeah you could "pad" the top your knee first if you have soft, weak or brittle bones..... 8) :wink:
then as noted above, double check to make sure the ejector rod did NOT come unscrewed...........