Self Help or Context Sensitive Help not functioning

Windows will display the help window with the directory tree in the left- side of the help popup, but the right side of the popup that contains the actual content of the help file will be blank!

By default, the Microsoft Windows settings may prevent you from viewing CHM help files (even if they reside on your local hard drive (C drive). 

To correct this:

This behavior is a function of the Attachment Manager, which applies a Zone Identifier to files downloaded from any source that is considered untrusted or at risk, such as the Internet Zone. This will occur if the .CHM file has been flagged as downloaded from an untrusted source, such as the Internet.

To resolve this issue, carry out the following steps...
  • Open file explorer and browse to the folder that contains the CHM file 
  • Right-click the .CHM file and choose Properties
  • On the General tab, put a check mark in the checkbox labeled "Unblock"
  • Click OK

For more info go to this Microsoft web page :