So I finish the Bleak falls barrow quest and decide to fast travel back to riverwood. When I arrive in riverwood all is fine for about a minute when all of a sudden this crazy woman runs at me brandishing a dagger intending to kill me. Then the entire town is hostile and chasing me. I can't for the life of me think why they would turn hostile.

Any ideas?

did you kill any chickens? People get upset when their chickens are slain.

You should attack a mammoth and lead it back to Riverwood for a mammoth Jihad.

I didn't kill any livestock. I didn't do anything. I'm scared to go back now incase they're still hostile

sleep for a few days
hopefully their mood will change.