Unable to connect one AirPod Pro to iPhone

recently I lost the right side AirPod from my pro 2s. I had find my on the AirPods turned off and I turned them back on to look for the AirPod. When I looked in find my, it said Finish set up or something like that and didn’t let me find the AirPods. One of the solutions that I found online was to forget and reconnect the AirPods. So I forget them, and now they refuse to connect since there is only one.

[Re-Titled by Moderator]

Original Title: Connecting 1 Airpod