A very common question, unfortunately.
Have you checked your Windows Update History to see if it has tried to install it in the past but has failed? If so, then you should be able to right click on the error message and obtain the error code. If you Google/Bing that, you should find
others with the same problem and the fix.
A common error code is 80240020. There exists a fairly easy fix that consists of merely deleting contents of a specific folder.
You might also try running the Microsoft Update Troubleshooter.