Samsung S8 and Aux in

[Haves1979]

Not sure if anyone can help with this. I usually plug my S8 into the head units of my cars with the 3mm jack plug. For some reason this has stopped working and if plugged into the head units it just plays through the phones speaker. The phone works fine with headphones so very confused! It also no longer plays with USB either..

Any help appreciated.

Cheers