may be there is an NGO that u can contact, there are lawyers out there who might take up u'r case for free. anyways sorry to hear the problem u'r in
I don't even know if you've consulted a lawyer (or plan to), but if you haven't, I think it would be a good idea before you give up.
I'm not sure how the system works in India, but even if there isn't an NGO, I'm pretty sure that you could go and get an opinion of a lawyer of whether or not you have a case, and they wouldn't charge you anything for it. At least that way you know for sure.
And like others have mentioned, if you have notes on the software, previous versions, algorithms, etc. written up...something to prove that you've been working on this software, you might have a case.
I wonder...if you have previous versions/drafts of the software, where the code is quite similar, and you can prove that those versions are yours, then is there any way you can prove that this final version was stolen from you??? These are just some of my thoughts, but I dont really know much, since I'm not a lawyer.
Anyways, I wish you the best of luck!
M.