Susanky,
There are several ways to show a hidden slide during a presentation.
Hyperlinking is just one, if you are not seeing the hyperlink maybe you
changed the colour of the hyperlink in the colour scheme of your
presentation. Anyway it works fine here.
If you know the number of the slide you can also press that number on the
keyboard and hit enter. Or alternatively, if you are on the slide just
before the hidden one, hit b on the keyboard and PPT will take you to the
hidden slide (this is in the Dutch version, could be another letter in the
English version, to find out hit F1 whilst in show mode and all shortcuts
will appear).
Why is the hyperlink not working, that is another question, maybe tell us
how you are proceeding to apply it.

Two ways to add a hyperlink:
1. Select text / shape
Insert > hyperlink
choose place in this presentation
select target slide
OK
2. Select text / shape
Slide show>action settings
hyperlink to
choose slide and select the correct slide
OK out