Ok, let take for example (this is only an example!) that you have a database 'osTicket', with database user 'admin_osticket' and that your admin password is abc123.
1. Connect to server with SSH, login as root.
2. Login to mysql: mysql -uadmin -pabc123 mysql
3. You should now have a 'mysql>' prompt.
4. Issue the following mysql command (all on one line), then press your ENTER key.
UPDATE `user` SET `Select_priv` = 'Y',
`Insert_priv` = 'Y',
`Update_priv` = 'Y',
`Delete_priv` = 'Y',
`Create_priv` = 'Y',
`Drop_priv` = 'Y',
`Reload_priv` = 'Y',
`Shutdown_priv` = 'Y',
`Process_priv` = 'Y',
`File_priv` = 'Y',
`Grant_priv` = 'Y',
`References_priv` = 'Y',
`Index_priv` = 'Y',
`Alter_priv` = 'Y' WHERE `User` = 'admin_osticket' LIMIT 1 ; Flush privileges;
5. Get out of mysql: At the mysql> prompt, type the word 'quit' and press ENTER key (do not put the quotes).
Explanation: This will update the table 'user' in the database 'mysql' for the user 'admin_osticket', giving all privileges to that user, and limiting the changes to just one (instead of multiple users). Then it flushes (or resets/reloads) the privilege tables and the changes are now in effect.
The main mysql database is where the database users are defined.
Please change this example to suit your exact needs, since you did not post any specifics...