What should I do if I don't pay back the money, answer the phone or return to WeChat?

Is there any evidence? If there is evidence, you can go directly to court to see if he still cares. Now it seems that the new civil code has clearly stipulated this point, and these old people must pay. If you don't really go to the meeting for a while, I believe that as a friend, it is generally understandable, but if you don't answer the phone for several years and then don't pay back the money, this is a typical attempt to evade responsibility, and such people should pay for their actions.