Hi Prasanna ,
Welcome to Healthcaremagic Forum.
There is no right medicine its all about the right timing.Since you have mentioned that you have underwent series of test for finding the cause of infertility
and i presume nothing came positive in your test and consider doing test to your husband, do semen analysis
find out the sperm count
If everthing comes negative there are drugs like Clomiphene
citrate which increases the egg release and maturation and increases the chance of conception.
Don't loose faith, you will surely succeed this.
All the Best.