Yes, stop mysql docker. just rename your appdata folder for mysql and then restore the old data to the appdata folder
If you don't have the root password, there's no way I know of to recover it. That would be a huge security flaw.
When setting up the docker for the first time without any previous data, you set the environmental variable for MYSQL_ROOT_PASSWORD. If you still have that environmental variable set, it likely tells you the password you set up when you first started the docker.
You can also set MYSQL_USER, MYSQL_PASSWORD, and MYSQL_DATABASE to set up those parameters as well.