The database can be (and is easy to) be restored.

however there's no way to do this without password resets (as all passwords do not match encryption so it mis matches passwords)

without backups it means you will need to reset the passwords (starting with serveradmin pass, going all the way down to user passwords)

How to reset serveradmin pass? After resetting serveradmin, I may login to panel and then reset other clients.

You can run SolidCP installer to update Serveradmin password. If it does not work, I am not sure if there is any other way to do it. But as you mentioned earlier, there is no live data so it is better to do a fresh installation.