My employer breached my employment contract, placed me on a Performance Improvement Plan which I satisfied and they still fired me. Can I sue?

I was hired on as a Director of Business Development to bring in new business for a Tax Advisory firm headquartered in Ohio. I work remotely in North Carolina. I introduced my new employer to a very large customer whose net worth is 5 billion dollars. My employment contract provides a 10% commission on everything I sell and a $100,000 annual salary. My sales quota for the year is $100,000. They recently purchased Salesforce.com to track sales. One of the partners in the firm purposely would not allow me access to see this large account. I believe this account signed a contract with my company and I was told not to have any contact with anyone in that account. I believe they did this so they did not have to pay me 10% commission and because the business they are doing in this large account may have satisfied the majority of my annual quota. My employer asked me if I had any other large compliance deals so they can plan for the work. This indicated to me that this large customer signed.