I had that happen as well recently. It looks like something is unregistering Fox help on the machine - perhaps when installing an application that installs its own set of runtimes and then uninstalling it.

Anyway to fix:

* Go to `C:\Program Files (x86)\Common Files\microsoft shared\VFP`
* Open an Admin command prompt
* Run `foxhhelp9.exe /regserver`
* Run `regSvr32 foxhhelpps9.dll`

This re-registers the help engine.

And as others mentioned make sure you do:

SET HELP ON
SET HELP TO 

(maybe before you do the first :-))

+++ Rick ---

>When I press "F1" or click on Help, or type "Help" in the command window, Help does not come up. Also no context-sensitive help.
>How can I correct this?
>
>I know the Help file is in the correct location (Options | File Locations points to a location and the help file is there).
>When I click on the Help file in Windows Explorer, Help comes up.
>
>This is VFP 9.1 running under Win/XP.
>Thanks.