On minecraft, i cant break blocks and i cant click stuff in my inventory

Put the summary of the bug you're having here
On mine craft, I cant break blocks and I cant click stuff in my inventory
What I expected to happen was...:
I downloaded a simply horses mod and it would work

What actually happened was...:
the mod didn't work and I couldn't click on things in my inventory and I couldn't break blocks

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ...