Lost the database?!

Hello, please help me, I made a tragic mistake: I was fixing the main page properties of my blog in the dashboard, and where it says the name of the directory (or the database? I don’t remember) I changed it, doing something like blogname.org, and I added /blog after the name.
Now of course wordpress doesn’t find the database anymore, but the dashboard has disappeared so I can’t log it to change that back. What can I do?!!! help….