I'm looking for a specific fic in which Sam is sent to an alternate reality (by Gabriel, and against sam's will) in which he died as a baby. Sam exists as a ghost in this reality and is connected with dean so can't move very far from him. Dean can sense sam, but doesn't know who he is at first: he doesn't remember his brother sam because his parents never talked about him. Eventually Dean figures it out, and with the help of his amulet his real memories return to him (he was sent from the real universe along with sam but his memories were erased).

Turns out that Gabriel was working with the fates (unhappily), who were trying to restart the apocalypse, and this was a trial run, trying to get sam to agree that his family would have been happier if he had died as a baby. However, Lucifer still escaped and the Winchesters still hunted. Things aren't better.

specific scenes:

Sam communicates through txts and the computer.
Dean finds sams headstone at the cemetery- confronts his parents.
Sam walks over deans amulet on the ground and dean can see him.
Dean and John trap Sam in a salt ring- it hurts sam.