If your Left Beats Fit Pro not working, there could be several reasons behind the issue, and troubleshooting it properly can help resolve the problem. First, ensure that the earbud is charged by placing it in the case and checking for the LED indicator. If the left earbud isn’t charging, clean the charging contacts to remove dust or debris. Another common issue is Bluetooth connectivity—try unpairing and repairing the device in your phone’s Bluetooth settings. Resetting the Beats Fit Pro by holding the system button on the case until the LED flashes can also help restore functionality. Additionally, check your device's audio balance settings to make sure sound isn't being directed solely to the right earbud. If the left earbud still doesn’t work after trying these steps, it may be a hardware issue, and contacting Apple Support for further assistance might be necessary.