Can't upload any sketches to Arduino Nano 33 IOT

I have an Arduino Nano 33 IOT and it worked a time very well.
But now I have the problem that I can’t upload any sketches to the IOT. I tried many sketches including the Blink sketch.

It is always the same error message:
“Beim Hochladen des Sketches ist ein Fehler aufgetreten.” (“An error occurred while uploading the sketch.”)
Attatched: bild1.png

I also tried to upload to the Bootloader (where the orange LED Blinks):
“Problem beim Hochladen auf das Board.” (“Problem uploading to the board.”)
Attatched: bild2.png

I tried different Windows 10 PCs. I updated all drivers. I tried the solutions on the page. And I read the post without success.

Thanks for your Help