A lot of the levels in Guardian Tales feature hidden mechanics. We believe that giving out spoilers and walk-throughs ruins part of the fun, but we also understand it is very frustrating if you are unable to fully clear a level, so here are some tips:
Hookshot is an ability that can only be used in certain spots. You can see where Hookshot is applicable by the following symbols:
Please also know that in order to use Hookshot you must be at the same height level as the target.
In the case of World 3-6, climb the stairs in front of the treasure chest and face right to see this option.