SecuPress — WordPress Security Plugin
SecuPress brings you a powerful and free tool to let you log in as a WordPress user if you only have the (s)FTP access.
You can create or edit a user, log in as an existing one.
If you need to deactivate a plugin without being logged in, you can do it.
Just use the top menu and you're done.
This script is free to use and you can contribute on github.
» Are you a WordPress user? Check out our plugin on SecuPress.me