Data type mismatch in criteria expression. i can find the solution : 



 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        Dim con As New OleDb.OleDbConnection
        Dim str As String = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source=..\VisitorPass.accdb"
        Dim sql As String
        sql = "Update Visitor set [password]='" & txtPassword.Text & "',FirstName='" & txtFirstName.Text & "',LastName='" & txtLastName.Text & "',Gender='" & txtGender.Text & "',MobileNo='" & txtMobileNO.Text & "',DateOfBirth='" & txtDateOfBirth.Text & "',VisitorAddress='" & txtVisitorAddress.Text & "'where ID='" & lblID2.Text & "'"
        con = New OleDbConnection(str)
        Dim cmd As New OleDbCommand(sql, con)
        con.Open()
        cmd.ExecuteNonQuery()
        Dim obj1 As New VisitorProfile
        obj1.StringPass = txtName.Text
        MsgBox("profile is updated")
        obj1.Show()
        con.Close()
        Me.Close()

    End Sub