Second, that’s a sad panda moment. I’ve had a few of those before.

Last, if you have the ability to edit the database it is simple. It is very much like adding a user but the key thing is changing the meta_value. This article does a good job of explaining that: https://www.godaddy.com/help/create-a-new-wordpress-admin-user-in-the-database-27023

Alternatively, you could also do something like: https://wordpress.stackexchange.com/a/4727