Thank you for your help. But where is the loop?
Thank you, it works!
I tried to delete the image from the post and insert it again and don’t link it to a file but it didn’t work so therefore I asked. But now with deleting the file and then uploading it again it works.
I have solved it. I thought maybe it was the YouTube video in a new post which had caused it, so by deleting the post, it worked again.
It does not help to drag it back.
This problem has been solved and might have been caused by editing .htaccess file in my blog folder.