I cant get on single player and when I try, it always says it crashed

Put the summary of the bug you're having here
I cant get on singleplayer and when I try, it just says minecraft crashed
What I expected to happen was...:
Describe what you thought should happen here
I thought I should have been able to get on singleplayer
What actually happened was...:
I cant get on singleplayer and when I try, it just says minecraft crashed
Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ...