Materials needed:
Replacement screen material
Screen spline
Spline roller tool
Scissors
Utility knife or razor blade
Flathead screwdriver or other prying tool
Measuring tape or ruler
Steps:
Measure the dimensions of the damaged screen. Measure both the width and the height, and be sure to measure the frame itself, not just the old screen material.
Purchase replacement screen material and spline. You can find these at most hardware stores or online.
Remove the damaged screen material from the frame. Use a flathead screwdriver or other prying tool to remove the old spline from the frame. Once the spline is removed, the old screen material should come out easily.
Lay the replacement screen material over the frame, making sure that it is centered and that there is enough material to cover the entire frame.
Use scissors or a utility knife to cut the replacement screen material to the correct size. Make sure to leave a few inches of excess material around the edges of the frame.
Starting at one corner of the frame, use the spline roller tool to press the new spline into the groove around the frame. Be sure to keep the screen material taut as you go.
Continue working your way around the frame, using the spline roller tool to press the spline into the groove and secure the screen material in place.
Once you have gone all the way around the frame and the new screen material is securely in place, use the utility knife or razor blade to trim off the excess screen material around the edges of the frame.
Inspect the screen for any loose spots or wrinkles. If you find any, use the spline roller tool to press the spline into the groove and tighten up the screen material as needed.
Finally, reattach the screen to the window frame. If necessary, use a flathead screwdriver or other tool to reinsert any clips or hardware that hold the screen in place.
That's it! Your window screen should now be repaired and ready to use.