Company not giving relieving and experience letter. How do I get them?

If your designation is not managerial or supervisory level, then you can submit a complaint to the area Assistant Labour Commissioner seeking the experience letter.  The termination letter issued by the management itself amounts to the relieving letter, and the management will not provide separate relieving letter as they have terminated your services as punitive measure. 

If you are aggrieved about the way of termination that without any fault of yours they terminated your services without affording you any opportunity to prove your innocence, you can file statement of claim before the above said Assistant Labour Commissioner for reinstatement of your services. 

If your job is managerial level, then you are beyond the jurisdiction of the Labour Department and Labour Courts and your grievance can be redressed by filing appropriate civil suit before the Civil Court.