That’s strange, accounts should never disappear from the wallet. Did you at some point uninstall the Anchor app? Only thing I can think of that could have caused it to disappear. Otherwise it’s a new bug we haven’t seen before, good news though is that all keys should still be on your device so we can probably help you recover it.
If you give me the account name and chain where you created the account I might be able to get some additional info, if you don’t want to share it publicly here on the forums feel free to drop an email with it to email@example.com instead.