Saint Judas

can someone please guide me on this?, I was loking on the web any tutorial or instruction to create scripts for my npc, i was trying to start with something simple, i need to trade with the npc, but the npc must restore the inventory for the next day, i spend around 5 days with no result, the npc only walk around and after he sell me the items he keep the pebbles but the items is not resotre. I really appreciate if someone can help me with that. Thanks.