Ok thank you all.
Preblem solved.
Steps to do:
1. find and eding constants.php 2. edit the constants.php to (for my only recovery mode):
After that, you can access the admin panel (just login normaly)
Try to disable step by step the plugins.
After that and if the forum is working again without issues edit constants.php in this:
Done, everything is working again.
Thank you all for your Help !