How to Fix a Stuck Window

Make sure the window is unlocked. Check the window for nails or wedges put in the window previously to keep intruders out.

Use a putty knife to press between the window and the frame on the inside. Tap the handle of the putty knife gently with a rubber mallet. Go all of the way around the window, working the putty knife back and forth.

Lift up and try to open the window. If you are not able to open it, you must go outside and do the same things as in Step 2 on the outside of the window. This should fix the problem.

Open the window. You can probably force it up the rest of the way even if it drags against something. As it begins to rise, you can force it gently if need be until you get it raised.

Sand the area holding the window (all around it) in order to remove whatever was making it stick. Most likely, the culprit was paint that has dried or some sort of dirt. Clean out the tracks of old paint and debris to fix this problem.

Take a candle and rub the wax along the area you just sanded. Now, pull the window back down and try to lift it again. It should be much easier this time. Open and shut the window several times to be sure it glides well.