If your phone won't read your SIM card, you can try to fix it by putting in a new one. If you're using a micro SIM card, you can ask your carrier to give you a new one.If your sim card stops working, then there are a few steps you can take to make sure your phone works properly. Make sure your sim card is clean and free from any debris or lint. Check that the contacts on both sides of the sim card are flat and not bent. Check that the contacts are not damaged.