Ok, found the code in the constants.php and changed to 0 - thank you.
Is possible for say problem is do if upgrade ? (Error message)
Sorry, I don't get this .. if you ask which error message(s) I got .. I don't have them anymore.
I have realised that I get an error message when I try to download the database backup but that is just a minor problem right now.
I noticed that after the upgrade the hackers script still was active somewhere (and about two weeks later it changed files like the index.php in the main folder) so simply uploading the upgrade files did not help.
That's why I am asking about deleting everything except the media folders and database.