My friend borrowed money and refused to pay it back despite repeated reminders.

1. A friend borrowed money but refused to pay it back after repeated reminders. If there is an IOU and there is no repayment date stipulated in the IOU, you can file a lawsuit directly with the location of the other party's court.

2. If there is no agreement on interest, you can only ask for the principal, but not the interest. Your current evidence includes: IOUs, records of loan requests on WeChat, and bank records of payment. These are all important evidence and can generally win the case.

3. After winning the lawsuit, if the other party still cannot fulfill the court's judgment, you can apply to the court for enforcement. As long as you know the property that the other party can enforce, you can enforce it. For example: bank deposit accounts, vehicles, real estate, etc.