Suggest Treatment To Improve The Chances Of Conception

I am kashish Lakhani . My age is 30 N my husband is 31. We are trying for a baby from 7 months N had a pre term delivery in June 2013. The baby was having breathing problem N was v weak N just survived for 2 days. So pls we really want our baby back. Pls can u tell me that why I am not able to get pregnant again.