If the seller is no longer taking calls regarding the sale, you may have been scammed with a lost or stolen watch.
Sadly, if you transferred cash to this seller with an app such as Venmo, you won't be able to recover your money. If you bought and paid for the watch through a service such as eBay or PayPal, use their dispute process.
M1 Mac mini, macOS 13.4; Watch, series 7 GPS/cellular, watchOS 9.5.2; iPad Pro 2nd Gen, iPadOS 16.5; iPhone 12 Pro, iOS 16.5; TV 4th Gen, tvOS 16.5; HomePods, audioOS 16.5 and Airport Express w/ Airplay 2