Different Aspects to Consider
There are 2-3 different aspects of this.
First, you would probably be more concerned about the laptop because it is of the client.
1. Do you have a backup of the data?
2. Do you have any confidential data that can be misused?
3. Do you have a mechanism to remotely disable the laptop so it can no longer be used?
4. How expensive is the laptop, and can you, as a contractor, replace it at your cost?
5. Do you have amounts pending settlement that you can leverage against the laptop?
Depending on the above, you need to decide on the action, including going to the police and filing a FIR, and taking their help to go to his house and recover the laptop. Do remember that you need to spend money for it; they don't do things for free.