Hello,
1) It is important to see the terms and conditions of your appointment to advise you most appropriately. Hope you have the appointment letter with you.
2) Usually there is a clause that tells about notice to be issued by either party in case of the company terminating your service or you are resigning.
3) The company can ask you to leave without notice; in such an event the company will be liable to compensate you. It is usually a month's salary in lieu of no notice to the employee.
4) Demand a relieving letter from the company.Demand the compensation. Of the company doesn't comply as per clauses in the appointment letter you will need to send a legal notice to the company.