My bathroom sink drain does not drain. This is true rather the push knob for the plug is up or down. It appears to be connected properly in the back. The sink is not stopped up with garbage. The problem lies in the push knob'plunger conncection.

My bathroom sink drain does not drain. This is true rather the push knob for the plug is up or down. It appears to be connected properly in the back. The sink is not stopped up with garbage. The problem lies in the push knob'plunger conncection.

Are you saying that when you pull up or push down on the knob that it doesn't affect the stopper?
If that's the case the Clevis(see image) needs to be adjusted. Push the stopper rod and the pivot rod all the way down and attach the clevis to the stopper rod. Hand tighten the knured nut holding the stopper rod. Now see if the stopper works. Good luck, tom