Answers to your query are as follows:
1. Can i file divorce ? , if yes then on which ground.
Ans On the ground of DESERTION you can file it. it is defined as follows:13(1)(ib) see last line.
Section 13 in The Hindu Marriage Act, 1955
(1) Any marriage solemnised, whether before or after the commencement of this Act, may, on a petition presented by either the husband or the wife, be dissolved by a decree of divorce on the ground that the other party
[(i) has, after the solemnisation of the marriage, had voluntary sexual intercourse with any person other than his or her spouse; or]
[(ia) has, after the solemnisation of the marriage, treated the petitioner with cruelty; or]
[(ib) has deserted the petitioner for a continuous period of not less than two years immediately preceding the presentation of the petition; or]
2. whats is better way for divorce either i file sec 9 if it will help me or can file directly divorce case .
Ans: Directly file divorce case.
3 If i file sec 9 first then can i convert it in to divorce case before decision after some time if she dont wants to come
Ans: Both sections are quite opposite to each other as such your case may not stand if you file under section 9 and then to section 13.
I have read more than 10,000 judgments and prepared Head notes which are published in many law journals. Further I worked a judicial officer for 20 years. Out of my experience I say that you have to file divorce case directly.
Section 9 in The Hindu Marriage Act, 1955
9 Restitution of conjugal rights. When either the husband or the wife has, without reasonable excuse, withdrawn from the society of the other, the aggrieved party may apply, by petition to the district court, for restitution of conjugal rights and the court, on being satisfied of the truth of the statements made in such petition and that there is no legal ground why the application should not be granted, may decree restitution of conjugal rights accordingly. 8 [ Explanation. Where a question arises whether there has been reasonable excuse for withdrawal from the society, the burden of proving reasonable excuse shall be on the person who has withdrawn from the society.