employer withhold paycheck,SOS

I signed an agreement with my employer when I asked the company to sponsor my H-1B. In the agreement, I was asked to work for the company for at least 3 years. Otherwise, I have to pay for the H-1B related expenses(estimate $6000). Now, I have worked for them almost 2 years and want to move to other state due to family matter. I gave them 3 weeks notice of my resignation. They kicked me out immediatelly and withheld my paycheck(including working hours and accumulated vacation). I consult a attorney regarding the H-1B expense issue. He told me the law against the employer pass the H1B expenses to the employee and it's illegal for my company withhold my paycheck. However, How can I get my paycheck back? It is too expensive to hire a lawyer. Please help. Thank you so much.