Did something stupid and cannot access my WordPress any longer

Hello,
I was setting up two WordPress installations (with one mysql-database) at the same time. It worked well until I mistakenly changed the URL of https://www.west-of-house.net/mountain (the one blog) to https://www.west-of-house.net/leserbrief (the other blog) in the wp-admin-menu.
Now I cannot login any longer: I get a login-screen but on entering my data I am referred to https://www.west-of-house.net/mountain/wp-login.php?redirect_to=%2Fleserbrief%2Fwp-admin%2F
which does not let me log in either.
Any chance to recover this?
HELP please….