Allow An Authenticated User to Change his/her Email Address

Hi All,
I have been searching since some days for the best approach one can have in order to allow an authenticated user to  change his/her email address.
This is the code I have but apparently it doesn't work and it doesnt even gives a error. The application seems to ignore it:
Change email address:
<asp:TextBox ID="txtEmail" runat="server"></asp:TextBox>
<asp:TextBox ID="txtPassword" runat="server"></asp:TextBox><br />
<asp:Button ID="changemailbtn" runat="server" Text="Button"  />                 
<asp:Label ID="lblErrors" runat="server" EnableViewState="False"
ForeColor="Red" Visible="False"></asp:Label>   
 
CODE ...