I have email id of FBA user and based on that I need username and password of that email id programatically. I guess I will get username but is it possible to get password of FBA user?
UserName and Password of FBA User is stored on the aspnet_Membership table of db where your FBA is configured. Again according to your configuration password would be either hashed or in Clear text format.
You can query the same using database query from the table programatically.
About password, if the password is in plain text then only you can fetch, otherwise if it is configured to be encrypted then you may not be able to fetch the same.