all my pdf files are blank and have the CCCleaner logo in the icon. pic attached
You have installed the new CCleaner Browser and associated PDF file types with it. (So that they open in the browser rather than Acrobat Reader or whatever you had them associated before).
If you don't want that then you simply have to change the file association back to Reader, or whatever you were using to view them before.
See this about associating a file to open with a particular app: