Broke my website

Briefly, I changed the url in Settings and broke it. Couldn’t access anything anymore.
googled around and followed various tips to no avail.
Final tip followed was to move wp-content, delete wordpress, reinstall & move wp-content back into the new installation.
New install of course creates a new database. What I can’t do get the original database to link to the new install. I’ve changed wp-config to the old database but just get a Database not found error.
I’m not that well up on programming etc but is there something in the database that needs resetting. My web host, Hostgator has phpmyadmin facility so I can get in and edit if necessary.
I have had to change the database password as I’d lost the original. Could this be the problem?
Thanks if anyone can help.