Dear Jose,
I use BPS Security plugin. I could not deactivate this plugin with a frontend because the website did not work (blank document appeared when gets admin or standard frontend).
I overrode all the code and DB contents with a version taken from an older backup and now everything is working properly. However I am a bit scared. Maybe the right option will be to delete all my server’s data and install everything from the scratch.
Thanks for your help Jose!
Best Regards,
Gandalf