Try force rebooting your phone. Hold the power and.volume button for 7-10 seconds. Phone will vibrate and then reset. This may fix it.
You can also try this if that fails: Activate the developer option in your Samsung Galaxy A50 first by going to Settings > Phone, and tap the seven-time build number. When allowed, go to the Developer option and scroll down to get the Media option. A’ Prevent USB audio routing’ option will be noted there. Switch on the switch by toggling this option.
See of that works.