Legal analysis: You can sue. If it is a real loan, the IOU is the best and most powerful evidence. It can generally be supported if the amount is not large. Large amounts need to be supported by transfer records.

Legal basis: "The People's Republic of China and the Civil Code"

Article 667 The contract is that the borrower borrows money from the lender, returns the loan and pays interest when due contract.

Article 668: Contracts shall be in writing, unless otherwise agreed upon for a loan between natural persons.

The content of a loan contract generally includes terms such as loan type, currency, purpose, amount, interest rate, term and repayment method.

Article 669: When entering into a loan contract, the borrower shall provide the true situation of business activities and financial status related to the loan as required by the lender.