My Minecraft Crashes Every Time!

Put the summary of the bug you're having here

What I expected to happen was...: My game would work fine, and I would play with my friend.
Describe what you thought should happen here: I would play and it WOULD NOT crash.

What actually happened was...: My game crashed each time I opened it.
Describe what happened here: It kept saying it crashed from an "Unexpected Error."

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ... Well, all I did was open Minecraft.
3. ... 5 seconds later, it crashes!