How do I find a bluetooth device which was once "forgotten" on an iPhone 6 (iOS 9.3.5)

I've been trying to connect my iPhone 6 with the latest iOS, with the bluetooth from my car.

Previously, it has been successful, but due to pairing issues, I clicked "forget this device" in attempt to resolve this issue, but now my iPhone does not recognize my car's bluetooth connection. My car although, still connects to other people's devices, so it is not my car's issue, it is the phone.

Please help me, it's been like this for months, and I'd like to connect it not just for music, but so I can answer phone calls safely, while driving.

Any advice or tips would be great. I've pretty much tried everything!! 😟😕

Much appreciated,

Sarah M.