Hello,
Just add ?language=xx at the end of your login url. Where xx is the language slug.
E.g: mysite.com/wp-login.php?language=fr
Did you install the language files (https://codex.wordpress.org/Installing_WordPress_in_Your_Language)?
The easier way to do this is to go in “settings” > “general”, set “Site Language” in German (or whatever) then put back in the language you want.
If the automatic installation doesn’t work for some reason, please follow the instruction for manual installation in the link above.
If the language files are already installed, please ask again.
Please, where can I check installed languages?
It should be in /wp-content/languages
