I downloaded a texture pack and now my minecraft wont open

I downloaded a texture pack and now my minecraft wont open

I was expecting it to work like the other texture packs just download, open and use.

I downloaded a texture pack, and I waited for it to transform my Minecraft into that texture pack, and it just kept crashing when I got to the Mojang introduction screen.

I need help I don't know what to do or how to get my Minecraft to work.