1. Record the name, quantity, value, characteristics and other information of the lost items, and try to provide accurate descriptions and evidence.

2. If the gym has monitoring equipment, contact the gym manager in time, request to retrieve the monitoring video to find the lost items, and try to find the responsible person.

3. If other people enter the gym, especially during the time when the lost items occur, it is necessary to find out their identity information, communicate and ask whether it is related to the lost items, and understand the reasons for taking the items.

4. Negotiate compensation with the gym management, provide relevant evidence and estimated value of lost items, and ask the gym to make corresponding compensation. You can ask the gym to provide a written claim agreement or compensation plan.

5. If you can't reach a compensation agreement with the gym management, you can consider bringing a lawsuit to the court and bringing a civil lawsuit to ask the gym for compensation. In the process of prosecution, it is necessary to prepare relevant evidence and materials, such as a list of lost items, valuation certificates, surveillance videos, etc.