Ok, try opening /usr/share/applicasions/yelp.desktop from a terminal as root (so su first or sudo)
and add
MimeType=x-scheme-handler/ghelp;
to the end of the file on a new line.
then
update-desktop-database -q
then
update-mime-database /usr/share/mime
Ok, try opening /usr/share/ applicasions/ yelp.desktop from a terminal as root (so su first or sudo) x-scheme- handler/ ghelp; desktop- database -q mime-database /usr/share/mime
and add
MimeType=
to the end of the file on a new line.
then
update-
then
update-
Does that fix it?