How to find items in DropDownList by Text in ASP.Net

i have a dropdown binded from database ;

now datavalue is INT

and datatext is string in my dropdown

now lets say in my dropdown the sequence is like this :

Value   |    Name

1             Pakistan

2             Saudia

now i have a string ;

string a = "Saudia";

now i want to know the DropDownsItemValue with respect to this string ....