Belt loops on pants tend to suffer a lot of wear and tear, not only when a belt is threaded through the loops but as they shift and are adjusted throughout the day. Even on the highest quality pants, belt loops can become dislodged over time. But rather than taking your pants to a tailor, get a heavy-duty needle and thread, and take a few minutes to make this easy repair yourself.
Fold under the edge of the loose belt loop twice to create a double hem. This step will provide greater reinforcement to your belt loop and may even make a future tear less likely.
Pin the hem in place, with the right side facing you.
Hand-stitch the loop to the pants, moving the needle from the wrong side of the pants to the right side and back down to the wrong side again.
Continue this up-and-down motion along the bottom edge of the loop. Try to catch only fibers of the fabric unless you want the thread to show on the right side of the fabric. Otherwise, move the needle up and down through the fabric freely.
Repeat the row of stitching at least twice to create reinforcement for the belt loop.