Legal analysis: If you borrow money without writing an IOU, the creditor can ask the debtor when it is in urgent need and when the debtor will pay back the money. You can use these conversations as evidence. If the debtor fails to pay back the money within two years, he can urge the debtor to pay back the money again. If the debtor still doesn't pay back the money, he can take audio-visual evidence to court to sue the debtor and ask him to pay back the money.

Legal basis: Article 63 of the Civil Procedure Law of People's Republic of China (PRC) has the following types of evidence: (1) documentary evidence; (2) Physical evidence; (3) Audio-visual materials; (4) Testimony of witnesses; (5) statements of the parties; (6) Evaluation conclusion; (7) Records of the inquest. The above evidence must be verified before it can be used as the basis for ascertaining the facts.