cant play any instance of minecraft un-modded or modded

Put the summary of the bug you're having here

What I expected to happen was...:
Describe what you thought should happen here

minecraft would load and i would be able to start playing

What actually happened was...:
Describe what happened here

game crashed and gave me a nullpointer error

Steps to Reproduce:
1. i launcher the game and i just crashed straight away before even reaching the mojang logo