it sounds like it's not the window, but the door itself ...
it's either the car sagging (longs rusted) or the door was bent upwards ...
if it's just the door, the easy fix is to open it all the way, roll down the window and SLOWLY press down on the end of the door. this will bent the hinges back to where they belong ...
if you bend it too far down, grab the rear bottom of the door and SLOWLY lift it up.
repeat until the door fits perfectly ...
Andy
PS: if it's rusted longs, buy a welder and report back ...