Multiuser problem in Asp.net

Revision 1
Dear friends,

Here, i've used public static string A; variable in my application.
Suppose, user1 hav A="1" and now user2 come to this form and he has A=2.
So, in this case original value of A for user1(which is A=1) replaced with user2(which is now A=2), But i want to keep both of the value saprately for both the users..

Note :
1) i used public string A; but during postback it lost its value.

i dont want to use session variable for this.

any help would be highly appriciated.
thank you.