How to Replace Window Screen Corners
- 1). Remove the window screen with the torn corner that you want to repair. Loosen any latches holding it in place and/or unscrew any retaining screws, using a flat-blade screwdriver.
- 2). Place the screen on a flat surface, such as a driveway or table.
- 3). Pull the end of the spline out of the channel with a pair of needle-nose pliers. Continue until you have pulled out the whole spline.
- 4). Stretch out a roll of new screen material over the frame. Cut it roughly to size with a sharp knife. It doesn't have to be exact.
- 5). Press the spline into the channel, starting in a corner, with the edge of a flat-blade screwdriver. Switch to the spline roller and continue pressing the spline into the channel around the screen frame.
- 6). Trim off any excess spline and screen with the sharp knife.
- 7). Replace the window screen in the window frame.
Source...