' Number with comma
Private Sub NumberTextBox_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles NumberTextBox.KeyPress
        Dim tb As TextBox = sender

        If Not (Char.IsDigit(e.KeyChar) Or Char.IsControl(e.KeyChar) Or (e.KeyChar = "," And tb.Text.IndexOf(",") < 0)) Then

            e.Handled = True

        End If

    End Sub

' Just Number
Private Sub NumberTextBox_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles NumberTextBox.KeyPress
        Dim tb As TextBox = sender

        If Not (Char.IsDigit(e.KeyChar) Or Char.IsControl(e.KeyChar)) Then

            e.Handled = True

        End If

    End Sub

Textbox Numeric Input

VB.NET