Note sure if you have tried this yet or not. But thought I would suggest it.
You can use device manager to view the COM ports on the system. BUT it may not be telling you the whole story unless it tell it too. There could be "hidden" devices you cannot see. You would think it is as simple as clicking on the "View" menu in device manage and selecting the "Show hidden devices" option. But this does not always show all hidden devices. So try this:
1. Open a DOS window as administrator
2. Enter set devmgr_show_nonpresent_devices=1
3. Enter start devmgmt.msc
The device manager will open. But even though you entered the command to show all hidden devices in the DOS window the hidden device will not be shown until you go back to the "View" menu and select "Show hidden devices". This will show ALL hidden devices now.
Now if you see some old ports that do not belong on the system you can delete them.
I added some screen capture to help.
Device manager 1 & 2 are befog using the "set devmgr_show_nonpresent_devices=1" option
Device manager 3 & 4 are after using it.