If a photograph is extremely old, rare or of archival quality, it's best not to repair tears; consult a photography professional. However, if the value of the photograph is primarily sentimental, follow these steps.
Things You'll Need
Gather the pieces of the torn photograph on a flat, dust-free surface. Make sure your hands are clean and dry.
Fit together the torn pieces on a piece of cardboard.
Place another piece of cardboard on top of the photograph and gently flip over both pieces of cardboard with the photograph in the middle.
Remove the top piece of cardboard.
Apply acid-free archival tape to the back of the photograph. Acid-free tape, available at photography and framing shops, will not cause any yellowing or staining over the years.
Use acid-free tape on the front of a photo only if the tape is designed for this purpose. If you do so, smooth out the tape carefully to avoid creating any air bubbles.
You can scan a damaged photograph onto a computer and use image-editing software to remove flaws, tears or signs of aging. If you want to display a delicate or an old photograph, it's best to use a copy.