Got a used watch can’t contact the person I got it from to unlock it what do I do

This support article has information about Activation Lock on your Apple Watch and how to turn it off as part of preparing a Watch for service or a new owner. --> About Activation Lock on your Apple Watch - Apple Support

Unless you have the original Apple receipt from the owner and can submit an unlock request, there is nothing you can do except recycle it.

Recycle it or turn it over to the police. There is no way to bypass the activation lock.

Either the seller did not properly prepare it for sale or it’s stolen.

Wait for their reply.

In the meantime, you can use it as a paperweight. It's not heavy enough to make a very good boat anchor or you could use it for that.

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