Program not showing up in Add & Remove Programs - can I uninstall?

I'm not sure whether this is in fact an XP problem, and am slightly worried it may languish fairly much unseen when it might be a more widespread problem, but here goes:

A program of mine has vanished from Add & Remove Programs since a couple of days ago.  Its files are still there in the Program Files folder, and when I attempted a reinstall I got an error message saying that there was already one instance active on the system and that I'd need to uninstall that and restart before I could reinstall.  Yet no sign of it in A&RP any longer, and my uninstaller programs can't see it to uninstall it!  If I go through the Start > All Programs command and try and uninstall it that way, I get the error message I referred to, and can't uninstall.

Does anyone know if there's a way I can force A&RP to recognise it, or do you have any suggestions as to how I can uninstall, please?

It is an XP/SP3 computer, admittedly, although as I said above I'm not sure how relevant that is.  The software is a program controlling a mobile broadband dongle.

Microsoft has a program that will attempt to fix this but it's only for Windows 7 and later. Microsoft used to have a tool called Installer Cleanup Utility but is now unsupported because of problems with Office. It is still available here. Run the program and look for your software. Only check highlight the software you are attempting to install, Reboot and see if you can reinstall then uninstall. If you do not see your program close out the program.

Edited by JohnC_21, 13 December 2017 - 08:41 PM.

Thanks John, I'd forgotten about that one.  However, when I run it I simply get a message asking whether I want to remove Windows Installer Cleanup from my machine - I assume that wasn't what you were expecting to happen?

Thanks John, I'd forgotten about that one.  However, when I run it I simply get a message asking whether I want to remove Windows Installer Cleanup from my machine - I assume that wasn't what you were expecting to happen?

No, I wasn't expecting that. I was expecting what is shown on the video at the Majorgeeks. Have you tried using Revo Uninstaller Pro? It has a free 30 day trial. If you have CCleaner is the program in the Add/Remove list under tools.

https://www.bleepingcomputer.com/download/revo-uninstaller/