The NPC design depended on pressing the same button through out the game but then when I created the final build it crashed and didnt work. so I had to go back program it again from scratch. This NPC was orginally created by script but then I had a really short time to fix it so i had to do it with playmaker.
Steps for this are:
1-enter collision box
2- activate dialogue 1
3-deactivate dialogue 1 and activate dialogue 2
4-deactivate dialogue 2 and activate dialogue 3
5-deactivate dialogue 3 and reset State.