Thanks Qazi.You are amazing in giving solutions.
I am able to set the password .I used Webdings font for that password field.I used a optional section which contains textbox for password and a variable that hides or unhides optional section.
If ddl status is Closed,i am setting that variable to true using code in form load.Added a conditional formatting for the optional section as if variable = false hide the section.
Added conditional formatting for Dropdownlist as,if variable=false and passwordtext not equal to <expexted password> disabel that control.
Solved my problem.
Also i am clearing thse variable and passwordtext to empty once the status is changed to open in dropdownlist_changed event.
Thanks.