Legal analysis: I didn't write the IOU, but the signature is valid. If the IOU is not signed by me, the IOU generally has no legal effect without other evidence to prove the establishment of the loan relationship, and the parties may request the local court to verify it. According to relevant laws and regulations, the parties have the responsibility to provide relevant evidence for their claims. The people's court shall investigate and collect evidence that the parties and their agents ad litem cannot collect on their own due to objective reasons, or evidence that the local people's court considers necessary for hearing a case. The people's court shall, in accordance with legal procedures, comprehensively and objectively examine and verify relevant evidence.

Legal basis: Article 669 of the Civil Procedure Law of People's Republic of China (PRC) concludes a loan contract, and the borrower shall provide the true information about the business activities and financial status related to the loan according to the requirements of the lender.