Can't get rid of old free version and cannot install newest free version
I have a free version of the antivirus program. I was trying to remove an old version and install the most recent version. Trying to uninstall wouldn't remove the old files so I tried to remove them manually but couldn't -- none of the usual ways of deleting stubborn files worked including the use of third party tools. I also tried a couple of the bitdefender uninstall programs for Antivirus Plus but they didn't work either.
So then I tried to install the latest free version of the antiVirus program hoping that it would update the old files to the new ones but unfortunately that didn't work.
So I am now in a state where the old version is inactive (it's been removed from the Windows registry), I can't get rid of any of its files, and I cannot install an updated version.
Please help me out of this mess. How can I delete the files for the older version of the free antiVirus program?