person username and password should be maintain in session for all the pages,

Session("username") = Login1.UserName

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
       Response.Cache.SetCacheability(HttpCacheability.NoCache)
       Login1.Focus()
   End Sub

   Protected Sub Login1_LoggedIn(sender As Object, e As System.EventArgs) Handles Login1.LoggedIn
       ' Session("username") = Login1.UserName
       validateuser()
   End Sub

Sub validateuser()
       Try
           sqlcon = New OleDbConnection(constr)
           sqlcon.Open()
           sqlcmd = New OleDbCommand("SELECT COUNT(*) FROM userrole WHERE username = '" + Login1.UserName + "'" AND username = '" + Login1.Password + "'", sqlcon)
           retval = sqlcmd.ExecuteScalar
           If retval = 1 Then
               sqlcmd = New OleDbCommand("SELECT role, emailid FROM userrole WHERE username = '" + Login1.UserName + "'", sqlcon)
               sqlrdr = sqlcmd.ExecuteReader()
               sqlrdr.Read()
               Session("username") = Login1.UserName
               getrole = (sqlrdr.Item("role"))
               Session("userrole") = getrole
               getemail = (sqlrdr.Item("emailid"))
               Session("reqemailid") = getemail
               Response.Redirect("~\Home.aspx")
               'Response.Write("you are valid " & Session("username") & " with role " & getrole)
           Else
               'Response.Redirect("~\Default.aspx")
               'lbl_msg.Text = ("Invalid login attmept")

           End If
       Catch ex As Exception
           lbl_msg.Text = ex.Message.ToString
       End Try
   End Sub