No Audio output for my Macbook Air connected to a Samsung External Monitor via USB-C

My Macbook Air is connected to a Samsung external monitor with built in Speakers via a USB-C. For the first week it worked well, with the Audio coming from the external monitor only. Overnight it just decided to not offer audio from the monitor.

I've tried these remedies :

1. Changed the ports and cables
2. Audio MIDI from Utilities (Creating a multi device and selecting it for output etc)
3. System Preference -> Sound -> selecting the correct output (It shows no audio controls)
4. Tried changing from the notification panel (The audio level controller is greyed out and still no audio from the monitor)

Help.