Problem with program uploading to board

Hello, I am having the follow error when trying to upload my code.

avrdude: ser_open(): can’t open device “\.\COM6”: The system cannot find the file specified.

avrdude: ser_drain(): read error: The handle is invalid.

When I select tools → Port it does not let me select port.

I have tried connecting my computer to another Arduino Mega and it was able to upload my code and was wondering why it was not uploading to my Arduino Mega.

Any advice is appreciated… Thank you!