Can I sue someone if I stole a business plan and proprietary information and contact?

Well, you may have something, but it certainly isn’t a clear-cut issue to me. If you had a non-disclosure agreement in place, then that would be a different story. Depending on the language contained in your business plan or your non-compete, you could have something there. Now, that said, if the non-compete is well-drafted then you can likely seek to enforce that. The end point is that I see a few potential options, but I’d say it comes down seeing what language is in the plan and the non-compete. Potentially, you could have other claims for the theft of the property. I would suggest seeking a consultation with a business litigation attorney so that you can discuss the details of what happened and review the documents in confidence.