When i had this issue i found a cheap case off amazon to pair with but here are the steps you can try to get them to pair,
Make sure your bluetooth is on when attempting to pair by holding down the button for up to 10-15 seconds if that does not work fully charge your airpods then open them up near any apple device with bluetooth on which should allow it to connect.
If this does not work what i did was buy a cheap case off of amazon to just pair them with the airpods themselves. this does work with all models but the case will be somewhat bad quality.
Hope this helped.
Link for the case : https://a.co/d/3QVUhEU