Hello,

Are you certain you used the correct email address and are on the correct server? It can be pretty easy to forget these after so long away. You can check which servers your account has a character on by going to the Recharge Center of your My Center page.
While not unheard of, accounts are not usually deleted. The primary exception for this is accounts of extremely low level that are sometimes purged during server merges.

If you are sure this error is not on your end, you can attempt to recover your account through the account recovery tool or by creating a CS ticket in game or in your user center. Here are the links to the two platforms you may use.

https://profile.oasgames.com/web/reset-password/get-user-name?lang=en-us

https://support-center.oasgames.com/