Hi Bob,
Most likely you are selecting the wrong port and/or you don't have a compatible device driver correctly installed.
Using Windows you don't need to "try" all the ports. The Windows Device Manager application allow you to just watch for the new entry that appears when you plug the USB end of the programming cable into the computer. The added COM port is the one and only port you need to choose. Anything that was present prior to that is irrelevant.
If you are using a programming cable with a Prolific chip, then the device driver that is automatically installed by Windows is not compatible. You must download, install and select the older Prolific v3.2.0.0 driver.
If you are using a programming cable with a WCH CH-340 chip, I have recently seen where Windows erroneously uses the Prolific driver. In that case you have to download the driver from the chip vendor and install it.
I used to advise against it, but I am more and more inclined to recommend that Windows users just go ahead and manually install the various common programming drivers (FTDI, WCH, Silicon Labs and Prolific) before plugging in their programming cable for the first time. For the links to all the drivers and instructions for the Prolific driver installation, visit the "miklor.com":https://www.miklor.com/COM/UV_Drivers.php website.
Jim KC9HI