Someone framed me behind my back and sent text messages to colleagues and leaders to slander me. I don't know who it is. What should I do now?

If it is serious, explain the problem with actions. If it's not too much trouble, go your own way and let them talk. Down-to-earth, not afraid of the shadow trick is useless. Still suggest using your own actions to illustrate simplicity. If he says anything bad about you, tell them what your original behavior was like with your actions.