Hi Seve91,
Since it did not work with just renaming the file. This time I would suggest trying to rename the file in Safe Mode. I have included the link 'How To Start Windows 8 or 8.1 in Safe Mode'.
Once you are in safe mode, please follow the same steps to rename the Flash.ocx.
1. From the Start screen type in My PC, and open it
2. Look for this file path c:\windows\system32\macromed\flash\flash.ocx
3. Rename the file Flash.ocx, to Flash.bak
4. Right click Flashutil_activex.exe, and click on Run as administrator. This will uninstall Flash Player
5. Next you will need to download, and install Flash Player
Hope this helps! :)