Hi,
I'm unable to add any mail account now: mailaccount_add_failed...
When you start fixmail script, you will see that it generates a vpop password. This will happen only if it could connect to mysql vpopmail db.
If fixmail script gives a notice, and watch this carefully, that if failed to connect to mysql, then the only chance left is to reset mysql password abd bring in harmony with mysql. If reset script for mysql does not remove this error, then reset mysql root password by mysql monitor.
Only then your fixmail script will be able to delete the domain from the system and add once again.