Unable to access Admin after re-installing backup database

I re-installed OC onto my new server, the website loads with no problems as did the Admin panel but when I installed my database from backup I can no longer access my admin panel. The wepages are there with the correct database but just no access anymore to admin.

I have checked the username and password and all is correct, it just keeps saying no user found.

Any ideas??

May be admin username was different.
Or just go to phpmyadmin using your cpanel.
Go to your database and then user table.
And check what is the username.