Accidentally pickpocketed him when fighting the deathclaw. Had to use the power suit to talk to him and continue the quest. Im at the part where you have to go to Sanctuary Hills, but I have to run from him because he is trying to kill me.

Is there a way to fix this? I've trapped him and tried seeing if it'd go away, but it doesn't.

Someone please help, I can't continue to play the game if this isn't fixed

You don't need to go to sanctuary. You can just go to Diamond city.

That still doesn't fix the whole problem with Preston.

Have you tried talking to him with weapon holstered? The game reads this as trying to surrender/give up a fight and NPC's may relent.

I just got off the game, but I'll try that. Thanks in advance!

It's easy guys. Surely you have an earlier save. Reload it.

Can't believe you actually tried to pickpocket the most important guys in the game at least in the early stages... why?

This is a game problem. OP wrote, that it happened accidentally - he probably was crouched for better targeting and clicked on Preston.

Try it out: If you are crouched (sneak mode) every friendly NPC is red, when your cursor is over him. If you activate, you are pickpocketing him, and in a fight that can happen accidentally.

I would recommend to go away and sleep/wait somewhere out of sight and out of the cell where Preston is, for 3 days. Do something else. Often the games NPCs 'forget' over time. In FO3 this helped, if for example Megaton was pissed on the players character.

I think if you sleep for 48 hours he'll forget about it. I accidentally shot Valentine shortly after he became my companion and he kept trying to kill me. I read on these forums that sleeping for 48 fixes this sort of thing, tried it and it works.

What I did with Valentine when he became hostile was I killed him, left and went to santuary alone then slept for 48 hours. When I saw him again it was like it never happened.