Expert Author Richard Peck
Microsoft Visual C++ Redistributable packages are pieces of software which act as "library" files.
This means that if a program wishes to include a certain type of functionality, the developer can simply include various files from a specific VC++ version, rather than having to code it up themselves.
Thus, when you use particular games, applications or other features of Windows, it may be the case that strange errors appear.
One such error is the "MSVCP100.dll is missing" problem:

The program can't start because MSVCP100.dll is missing from your computer

The cause of the error, as mentioned, is the "MSVCP100.dll" file is missing from your PC.
This file is part of the VC++ Redistributable 2010 package (MS = Microsoft, VCP = Visual C PlusPlus, 100 = version).
Whilst you may have the package installed, it is often the case that its DLL files are either missing, corrupted or overwritten.
To fix the problem, you need to ensure that the MSVCP100.dll file is back on your system.
This can be done by following the steps below...
Solution
1. Reinstall VC++ 2010
The first step is to re-install VC++ 2010.
This is a free process and can be accessed using the following steps:
  • In Windows 7, click on "Start" > "Control Panel" > "Programs and Features"
  • In Windows 10, right-click on the "Start" button > select "Apps and Features"
  • Scroll down to any reference to "Microsoft Visual C++ Redistributable"
  • Ignore any listing other than the 2010 version
  • Click on the listing and select "Uninstall"
  • Restart your PC
  • After restarting, click onto the Internet and look for "Visual C++ 2010 download"
  • You should find a Microsoft page as the first link
  • Click onto it and click the orange "Download" button
  • Let the application download
  • Run the installer
  • Follow its steps
  • After it installs, restart your PC
This will have re-installed the VC++ 2010 package as a whole, thus replacing the MSVCP100.dll file on your system.
If you try the application again, it should work this time. If not, move onto the next steps.
2. Reinstall Any Application Causing The Error
If the above does not work, it generally means that you have a problem with a particular application.
The way to fix this is to essentially reinstall the application triggering the error, which is very simple:
  • In Windows 7, click on "Start" > "Control Panel" > "Programs / Features"
  • In Windows 10, right-click on "Start" > select "Apps and Features"
  • Locate the application you wish to re/un install
  • Uninstall it
  • Restart your system
  • Install a fresh copy of the application again
As mentioned, the reason this works is because many applications try and replace the MSVCPxxx.dll files on your system.
Reinstalling the application should fix the error for you.
3. Manually Replace MSVCP100.dll
If you still have no luck, you need to replace the MSVCP100.dll file manually on your system.
To do this, you need to find a version of the file online (which isn't that difficult) and replace it:
  • Search online for "MSVCP100.dll download"
  • Select the first link which appears (or look for DLLMe.com)
  • Download the file to your system
  • Browse to C:/Windows/System32
  • Extract the file into that folder
  • Once this is complete, press "Windows" + "R" keys on your keyboard
  • Type "cmd" and press "Enter"
  • Into the black box which appears, type "regsvr32 msvcp100.dll"
  • Press "Enter"
  • Once this completes, restart your system
  • Try your application again
This should provide the application with the file it requires. Whether it fixes the problem, we'll have to see.
4. Clean Out Registry Errors
Lastly, cleaning out any registry errors may provide the system with the ability to read its DLL files again.
What most people don't know is that the "registry" (which is the central database for Windows - responsible for storing all the settings for your system) stores a large list of available DLL files - and their locations.
The problem for most systems is that this database / list can often become damaged, preventing your applications from locating the file.
To fix it, you can "clean" the registry...
  • You need to download a "registry cleaner" application
  • CCleaner is the only tool that's worth using in 2018; there are others, but CCleaner is the most trusted (and it's free)
  • From here, you need to run the program and let it scan all your registry files/errors
  • If it finds any, let it clean them
  • Restart your system
  • Try the application again
--
If you still cannot get the application to work, it means that you have some further problems with your system.
It's likely the case that a piece of software (typically a game) has overwritten the original MSVCP100.dll file with its own.
To resolve this, you either need to get some insight from someone with specific experience of your system, which can be attained by going to the likes of SuperUser or MicrosoftAnswers.