Did something really stupid… changed address in Admin Settings

I did something really stupid and now I am totally blocked. Tried to find the answers through the forum but so far no luck.

I went into the Admin / Settings panel and by accident I changed the url of my site from the https://localhost:8888…. (don’t remember exactly what the default was after setting it up through MAMP). I input the url of my domain name.

When I clicked on my bookmarked admin page, I got the message:
We were able to connect to the database server (which means your username and password is okay) but not able to select the database.

I tried two things to resolve the issue but neither (nor the combination of both of them) worked:
1. Opened the wp_config.php file and renamed the database from the domain name to database name. That didn’t work so I tried a combination of the wordpress/databasename – still didn’t work. Then tried to change it to https://localhost:8888/wordpress – still didn’t work.
2. Went into MyPhp, selected the database, browsed the Options and then changed the site URL from the domain name to the https://localhost:8888/wordpress/databasename – still did not work

Please please please someone help me on this one. I really don’t want to start fresh again on my site. I obviously did not make a back-up before doing this stupid mistake.

Any help is greatly appreciated.

Andrea