Keeps on crashing when i downloaded a texture pack

Put the summary of the bug you're having here

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

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

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...Login to Minecraft
3. ...Click play then opens but it goes to screen crashed sorry for your incovenience