Any chance that the toolbox/suite you installed is PSAT (power systems analysis toolbox)?
The help command in matlab stops working after adding PSAT to matlab's path
that's because the help command of matlab calls a routine called "settings" in the folder: "%matlab-root%\2018a\toolbox\matlab\configtools\settings.m, and psat also has a routine called "settings.m".
When you call matlab's help, you will find the culprit in the file named: "getTopicHelpText" in the sub-function at the bottom named: "useSingleSource(hp)"
to solve this problem, you must change the name of PSAT's file to something else; and cross-check if any other psat files use this routine
alternatively, in matlab's "getTopicHelpText" routine, change the "settings" command.
if the toolbox causing the problem is NOT PSAT, then something similar has happened for other reasons. the thing is, the code to fetch the help-text from any file, is done inside a try-catch-end block in matlab's help routine (help.m)