My game won't start after a crash

I was in dalaran a while ago and then suddenly crashed I thought sure just a minor error it is an old game... low and behold I can't start the game now it says Critical error Failed to read file Shaders/vertex/vs_1_1/ui.bls. I cannot for the life of me find this file does anybody know how to fix this without uninstalling all the beautiful addons I have?

This means the client you downloaded is corrupted. You can download the game again and then copy the Interface\Addons and WTF folders over the new client. That way you won't lose your addons or settings.