In the Device Manager you'll have a listing for Ports. Click on the + sign to the left of that. It should open a list which should include a Communications Port (COMx). Right click on that and from the menu that appears, select Properties. A new box will open. On the General tab in the center of the box it will say Device Status. That should say "This device is working properly". If not, you won't be able to connect through that port.
If there is more than one Communications Port listed, do this for each one.
Let us know what you find there.
BTW, if your computer happens to have a serial port on the front and another one on the rear, try the opposite one from the one that you have been trying.
Dick