Hopefully you took a backup of the database because you now have no employee records for "Named" login type.  Please restore your backup and if by some chance you didn't take a backup, then all related employee records will have to be created.

We still have around 70K records in Employee table, but none of them are visible via Employee and Department screen. I have created the new record via screen and after create it is not visible in screen

Did you perform a "commit" at the database level?  Can you perform a "restore" or "cancel" or "rollback"?  How many data records were in this table before?  It is possible the system needs to make background adjustments for any related links with other tables and this could take time to refresh.  This is another reason never adjust table data records outside of the Asset Manager applications.  You should still restore from a backed up version.  You could also try and perform a database repair via Designer application but I cannot guarantee this will fix your issue.

I came to know now that DB dont have any backups, and DB we had already executed Commit. We usually wont do this kind of activity via databse, as there were more records we had to perform this, now it seems completely stopped working.

I have created new user and after clicking the create button in screen this record is also going invisible. but when i logged into Automated process manager with this user im getting the attached errors

Either that new user does not have 'Administration rights (bAdminRight)' flag check under Profile tab OR your database is corrupt to the point the APM cannot use that login (if the flag is checked).

I would also take a dump from the backend of your amEmplDept for those 70k records in case they need to be loaded again (ie. import module of AM).  Did you have 70k records before or is this what is left after your SQL commit?

It won't hurt to check with your DBAs to determine whether they take a database backup as this will help if they do.

I had approached DBA's and they said they dont have any DB backup's with them at all. if at all restore needed, i need to go with storage team and the whole server restore point. which is time consuming approx 2 working days and to my bad luck this happened on friday night .

for the new user we had checked the Admin rights under the profile tab, looks like whole database is corrupt. we need to go for whole backup restore point from server with the help of storage team. is there any other way we can do it restore back or fix the issue which are mentioned above.

But the new user is able to login via application designer and able to see the database structure, looks like data got corrupted.

Strange how the new user can log into Designer but not APM.

Even i also think the same. and when i launch APM, its showing some dll missing and im not sure what to do...if no solution found i need to wait for two days then needs to raise a request to get it restored