Does anybody remember the first scene when he killed teddy? How it happened while he met Teddy again and the film ended with Teddy is dead?
Ok abdelaziz, I' not sure if you've grasped the concept of Memento...
As funny as your frantic panic is, I think I'd better explain....
The film is in reverse order, so the start is the end and vice-versa.
Each 'segment' begins just before the preceding one. So although we see Teddy die at the start, he is actually dying at the end of the films chronology.