Hello Ayaz,
You should contact the cbse board or the head office since your migration and leaving certificate has not been issued. You should write a letter to the respective board head office for the issual of the above documents. The documents will be sent to you withing 4-8 days depending on your location and delivery of the post. You should also attest the above documents from a higher gazetted officer for admission into colleges and for counselling and verification process. You can also try contacting your college admin/principal who can contact the head office of cbse board and issue your documents as soon as possible.