thanks for the solution..
but i have done with my below solution
For Each CurrentForm As Form In Application.OpenForms
If CurrentForm.Name = "form2" Then
Dim Form2Instance As form2 = DirectCast(CurrentForm, form2)
If Form2Instance.TextBox1.Text = "some text" Then
Form2Instance.BringToFront()
Exit Sub
End If
End If
Next
Dim form As New form2("some text")
form.Show()