Code:
Private Sub Command1_Click()
Text1.Text = Replace(Text1.Text, "A", "a")
Text1.Text = Replace(Text1.Text, "B", "b")
Text1.Text = Replace(Text1.Text, "C", "c")
Text1.Text = Replace(Text1.Text, "D", "d")
Text1.Text = Replace(Text1.Text, "E", "e")
Text1.Text = Replace(Text1.Text, "F", "f")
Text1.Text = Replace(Text1.Text, "G", "g")
Text1.Text = Replace(Text1.Text, "H", "h")
Text1.Text = Replace(Text1.Text, "I", "i")
Text1.Text = Replace(Text1.Text, "J", "j")
Text1.Text = Replace(Text1.Text, "K", "k")
Text1.Text = Replace(Text1.Text, "L", "l")
Text1.Text = Replace(Text1.Text, "M", "m")
Text1.Text = Replace(Text1.Text, "N", "n")
Text1.Text = Replace(Text1.Text, "O", "o")
Text1.Text = Replace(Text1.Text, "P", "p")
Text1.Text = Replace(Text1.Text, "Q", "q")
Text1.Text = Replace(Text1.Text, "R", "r")
Text1.Text = Replace(Text1.Text, "S", "s")
Text1.Text = Replace(Text1.Text, "T", "t")
Text1.Text = Replace(Text1.Text, "U", "u")
Text1.Text = Replace(Text1.Text, "V", "v")
Text1.Text = Replace(Text1.Text, "W", "w")
Text1.Text = Replace(Text1.Text, "X", "x")
Text1.Text = Replace(Text1.Text, "Y", "y")
Text1.Text = Replace(Text1.Text, "Z", "z")
End Sub