Please follow the steps-
1. Login to the control panel.
2. Go to the Databases menu > MySQL > MySQL DBs.
3. Click on the database for which the user has disappeared.
4. Click on the Add icon in front of the Database users section.
5. Pick the user from the dropdown menu.
6. Select the user role as DBA.
7. Click on grant and the user will be attached with the database.
]]>