Ok. Last ditch effort before moving on to something more drastic.
See if downloading and merging the .reg files for the listed Directory, Drive, and Folder options in the tutorial below may be able to help. They will restore the default associations for these items.
If that doesn't help, then create a new administrator account, and see if they have the correct icons in it.
If it does, then you could use that account instead, and just copy any files and shortcut from the old account into the new one, and delete the old account when ready.