I bought an iPad three years ago. I played with it for a couple of months before packing it in storage for a renovation. Forgot about it and found it again last

I bought an iPad three years ago. I played with it for a couple of months before packing it in storage for a renovation. Forgot about it and found it again last week. Apple has since deleted the account that my iPad synced with. I am completely unable to use the iPad after upgrading it to the latest iOS, as my account simply doesn't exist. I even tried registering an account with the same username/password combo. It registered, but the iPad won't have it. If there is a way to circumvent iCloud protection, I'd love to know.