Did you see any error messages in your ‘Console’ window when your project stopped? If so, can you copy and paste them here so we can take a look?
Your laser may be losing connection due to a loose USB connection, a USB port sleeping, static discharge causing the controller to reset, or insufficient power supply leading to a brown out condition.
Here are some resources to help you troubleshoot these issues:
https://docs.lightburnsoftware.com/Troubleshooting-Connection.html#losing-connection