private void TextBox1_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = (e.KeyChar == (char)Keys.Space);
string Symbol = e.KeyChar.ToString();
if (!Regex.Match(Symbol, @"[а-яА-Я]|[a-zA-Z]").Success)
{
e.Handled = true;
}
}
if (e.KeyChar != (char)Keys.Back && !Regex.Match(Symbol, @"[а-яА-Я]|[a-zA-Z]").Success)