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. 

​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.