A quick, free, easy, and effective method of replacing the Window's rundll32.exe file when it is found to be missing or damaged.
The Internet abounds with ineffective and complicated methods to repair or replace a missing or corrupted rundll32.exe. The most common suggestion is to use the Windows files checker (sfc /scannow). It would be nice if File Checker fixed the problem, but it doesn not. However, the simple solution presented below is known to work.
Simply, rundll32.exe is a Windows program which loads into memory and executes routines contained within dynamic link library (.dll) files.
For example, when you click on "Change date and time settings", rundll32.exe loads the necessary code from the appropriate dynamic link library file. Another task which relies upon rundll32.exe is configuring how you want the Windows Search function to operate.
The most common problem with rundll32.exe is that becomes corrupted by malicious code (computer viruses, etc.) and/or it gets deleted or quarantined by your anti-virus software after it has been infected by malware.
The solution, one that's easy and has worked every time for me, is to find a good duplicate copy of rundll32.exe on your computer and use it to replace the bad or missing copy.
This solution won't work if ALL the copies of rundll32.exe are missing or corrupted, but that's an unlikely situation.