can't uninstall or reinstallcanon camera software

My camera software began to play up when looking at raw images. I decided to
uninstall and reinstall to see if this would cure the problem. Some of the
files ininstalled successsfully but others kept coming up with 'system not
modified as wizard was interrupted. The program is still listed in the add/
remove list and I cannot remove or reinstal it. However when I run the canon
browser it says I need to add a file to view the raw images.
How do I remove the canon software completley from my computer sop that I
can completely reinstall everything. It has worked fine for 2 years or so.
Thanks in advance to anyone trying to help.