Need help to remove the error in Windows

I am getting an error message which says ‘Windows cannot open the rundll32.exe.Ffor opening this file; it is to be known that which program created this. To detect the program windows can search for online or manually can select.’ It is coming when I am clicking anything. I cannot get in to the Control Panel for removing the programs. I also tried the download, nothing has happened. I will be thankful for your help to get out of this problem.
