HELP, broke website by copying database

I tried to create a duplicate of a registration database within my website (which was entirely written by somebody else, hence I’m unfamiliar with the back end) without realising I was copying the database relating to the whole site. I renamed the database esrgroup_newesr to esrgroup_newesr2016 and then using operations-copy in myPHPadmin on cPanel copied the database with structure only to the name esrgoup_newesr. In my mind I was duplicating a database structure whilst storing the old data.
I instantly realised this had killed the webpage (www.esr-group.org) so reversed my actions by renaming the new structure only database, and then renaming the original from esrgroup_newesr2016 back to esrgroup_newesr as it had originally been called
This hasn’t restored the site though. On going to the wp login page http://www.esr-group.org/wp-admin I get the error message:

We were able to connect to the database server (which means your username and password is okay) but not able to select the esrgroup_newesr database.

Are you sure it exists?
Does the user esrgroup_newesr have permission to use the esrgroup_newesr database?
On some systems the name of your database is prefixed with your username, so it would be like username_esrgroup_newesr. Could that be the problem?

Any suggestions of how to fix this would be much appreciated. Other help requests with this error message seem to relate to installation not an idiot killing their webpage by renaming the database so didn’t help. If I can get the site back on line I’ll not be meddling with a back-end I don’t understand again! Many thanks.