This will only allow numbers to be entered.

VB Code:
  1. Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
  2.         If Not Char.IsNumber(e.KeyChar) Then
  3.             e.Handled = True
  4.         End If
  5.     End Sub