So I was at the point where I had to choose between factions And I either had to go talk to the brotherhood, minutemen and the railroad. So I decided to go to the minutemen but before doing so I went to kill off the railroad and the brotherhood (dont ask why I just felt like going on a spree). Then I went to talk to preston but.... for some reason he just ignores me the dialogue options dont pop up I have tried everything from sending him to another settlement to attacking him.
Also for some reason all the auto saves that I have are from after I killed of the brotherhood and the railroad and the last one before that was from a week ago.
How do I fix preston, anyone have expienced the same?

Either restart the game from scratch or load a savegame before you start the spree. Youre not suppose to do that, unless you follow the MQ lines and do what certain questgivers says. It's up to you what faction should die or live, but if you really mess up MQ lines.....

Cheers,

-Klevs

SO theres no way to fix preston? restarting from before the spree would be like 20 hours of gameplay ago

You just learned a very valuable lesson...

ALWAYS do a manual save before killing sprees.