This issue comes up from time to time. Windows 7 was the last version to include the intrinsic ability to use .hlp files. However there are still many, many, useful .hlp files out there and many don't have sources to be able to convert to the .chm or the newer help format.
There is a solution that enables using .hlp files for windows 10 and windows 11. Here is the link.
I use on Win 11 and Win 10 systems.
https://www.majorgeeks.com/files/details/winhlp32_for_windows_10.html you'll download winhlp32.msi to install the 'original' 32 bit .hlp utility.
Example under win 11 attached
John Z
