Windows tend to stick because of paint that has oozed into the window sash, channels that need to be cleaned or other issues involving paint. There are several simple ways to break a light bond. The easiest way to tackle a stuck window is to use a stiff bladed putty knife into the various cracks around the problem window casing and tap the handle gently with a hammer. You can also wrap a block of wood in fabric and lay it against the bottom of the window frame, first on the one corner and then on the other, and lightly tapping the block with a hammer. In both cases, please be cautious since overenthusiastic swings or near misses could leave you injured or needed to replace the glass in the window.
If the easy ways do not work, then you might have to get a little more aggressive in opening that window. The next thing to do is get a block of wood and pry bar and head outside.
1. Place the pry bar under one end of the sash, resting on the block of wood.
2. Rock the bar backwards.
3. Repeat the set up and action on the other side of the sash.
4. Repeat the prior steps, moving closer to the center of the sash with each move until you have lifted the entire sash.
5. Try lifting the window. It should be mobile when the sash is raised evenly.
If your window is still being stubborn, do not fear. There are still other things to try! The next process only requires a utility knife or single edge razor blade and some patience.
1. Run the utility knife or razor blade through the cracks around the problem window casing. This should break a paint seal.
2. Rattle the sash gentle to free it from the window.
3. Repeat as necessary until you can lift the window, it can be a slow process and requires some patience. Remember to work gently, slowly and carefully.
If your window is still stuck, you might need to take some more aggressive steps, involving removing the window and clearing out the cause of any problems.
1. Remove the window stop from the frame. If the window is painted, you will most likely have to cut through the paint with the utility knife or single edge razor blade.
2. Take out the window sash.
3. Look for excessive paint in the crack on both sides of the window, the bottom and where the sash and sill.
4. Scrape any of the unnecessary paint away with a putty knife or chisel.
5. Sand the edges of the window sash and stop.
6. Rub the freshly sanded pieces with hard candle wax or soap to lubricate them.
7. Replace the sash and stops, and try the window again.