The plunger in the trip lever asembly is frozen in the closed position. Is there anything e.g.. vinegar,Liquid Plumber etc. I can pour into the overflow pipe to remove corrision thus allowing the plunger to move freely and/or be removed?

Spray WD-40 On the walls of the tube Do not spray on top of the plunger but around the plunger touches. Let it set for a while and try again. Good luck, Tom

Another trick here would be to take a metal coat hanger and cut it so that you can make a hook on one end.

Then, go fishing for the plunger. If you are lucky you'll catch the cross bar and can pull the plunger up and out without much issue!

Good luck!

Mark