Loading Inventory

How can I load saved Inventory?

I’m very tired of trying to get this to work I tried so many things and none of them work even dealing with YouTube videos but none of them helped.

In the easiest way possible how can you load saved content in my case is dealing with saving Strings and trying to load strings what I’m trying to do is simply use a Key like system where a certain key will unlock a level when that key is stored and loaded.

-Thanks
-Ernesto
(EFL)