Фильтр ввода в textbox

    Private Sub TextBox1_KeyPress(KeyAscii As Integer)
        Select Case KeyAscii
            Case 65 To 90 
            Case 97 To 122 
            Case Else
                KeyAscii = 0
        End Select
    End Sub

    Private Sub TextBox1_KeyPress(sender As System.Object, e As System.EventArgs, KeyAscii As Integer)
        Select Case KeyAscii
            Case 65 To 90 
            Case 97 To 122 
            Case Else
                KeyAscii = 0
        End Select
    End Sub

Public Class Form1
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As  _
System.EventArgs) Handles MyBase.Load
        TextBox1.MaxLength = 1
        'TextBox1.Text = My.Computer.FileSystem.CurrentDirectory
 
    End Sub
    Private Sub textBox1_GotFocus(sender As Object, e As System.EventArgs) Handles TextBox1.Enter
        If TextBox1.Text <> [String].Empty Then
            TextBox1.Text = ""
            TextBox1.Select(TextBox1.Text.Length, 0)
        End If
    End Sub 'textBox1_Enter
 
    Private Sub textBox1_Leave(sender As Object, e As System.EventArgs) Handles TextBox1.Leave
        TextBox1.Text = TextBox1.Text + ":\"
 
        textBox1.Select(0, 0)
    End Sub
 
 
    Private Sub Text1_KeyPress(KeyAscii As Integer)
        Select Case KeyAscii
            Case 65 To 90 'Заглавные Лат
            Case 97 To 122 'строчные Лат
 
            Case Else
                KeyAscii = 0   ' остальные символы запрещены
        End Select
    End Sub
 
    Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
        'Dim NewPath As String
        Dim ErrorMessage As String
        Try
            My.Computer.FileSystem.CurrentDirectory = TextBox1.Text
 
        Catch ex As Exception When TextBox1.Text = ""
            ErrorMessage = "You must enter a path."
 
        Catch
            ErrorMessage = "You must enter a valid path.  If trying " & _
            "to access a different drive, remember to include the drive " & _
            "letter."
        Finally
 
            If ErrorMessage <> Nothing Then
                MsgBox(ErrorMessage)
            End If
        End Try
        'MsgBox(My.Computer.FileSystem.CurrentDirectory)
 
    End Sub
 
    End Class