How do you restore database user manually from mysql.sql file?

[JonathanLIVE]

I just had a really strange thing happen. Customer with 25 WP blogs.. suddenly all of his database user names are GONE... I downloaded the last backup and the file where this is normally stored is the file in the root that is mysql.sql.

I went back a week and found all the names in there.. now I need to restore it but I haven't been able to find any way to do this. How can I take the mysql.sql file from the backup file and put back all the database user accounts... the databases are still there.. it's JUST the user names gone...

Do any of you have any idea what would cause this? I know it's not user error. Please I need to get these sites back up quick!

Thanks

[WestBend]

slow method : just create the db users again and grant them the rights.
Check the WP files for username and password required by each blog for each database.