How to avoid color changes when button is disabled?

You need to use the EnabledChanged event to set the desired color. Here is an example.

private void Button1_EnabledChanged(object sender, System.EventArgs e)
{
Button1.ForeColor = sender.enabled == false ? Color.Blue : Color.Red;
Button1.BackColor = Color.AliceBlue;
}

Use the desired colors according to your requirement.

Also you need to use the paint event.

private void Button1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
{
dynamic btn = (Button)sender;
dynamic drawBrush = new SolidBrush(btn.ForeColor);
dynamic sf = new StringFormat {
    Alignment = StringAlignment.Center,
    LineAlignment = StringAlignment.Center };
Button1.Text = string.Empty;
e.Graphics.DrawString("Button1", btn.Font, drawBrush, e.ClipRectangle, sf);
drawBrush.Dispose();
sf.Dispose();

}

To get less-fuzzy text, use the TextRenderer class instead:

private void Button1_Paint(object sender, PaintEventArgs e)
        {
            Button btn = (Button)sender;
            // make sure Text is not also written on button
            btn.Text = string.Empty;
            // set flags to center text on button
            TextFormatFlags flags = TextFormatFlags.HorizontalCenter | TextFormatFlags.VerticalCenter | TextFormatFlags.WordBreak;   // center the text
            // render the text onto the button
            TextRenderer.DrawText(e.Graphics, "Hello", btn.Font, e.ClipRectangle, btn.ForeColor, flags);
        }

And the Button1_EnabledChanged method as in Harsh's answer.