No serial port shown

Hi Guys,

my arduino uno r3 gives me that error:

avrdude: ser_open(): can't open device "\.\COM4": Das System kann die angegebene Datei nicht finden.

I uploaded my code yesterday and it still works but i can't upload a new code. The board still gets power by the USB connection and the led on lights.

I tried the reset button but still doesn't help.

Anything i can try?

Thanks in advance.

Is it plugged into a different USB port? Windows will give it a different COM port number in that case; check tools -> port.

Have you switched cables? Bad usb cables are a shockingly common.