Public Class SendInputs

    Private Const KeyDown As Integer = &H0
    Private Const KeyUp As Integer = &H2

    <DllImport("user32.dll")> _
  Private Shared Function SendInput( _
        ByVal nInputs As Integer, _
        ByVal pInputs() As INPUT, _
        ByVal cbSize As Integer) As Integer
    End Function

    <StructLayout(LayoutKind.Explicit)> _
   Private Structure INPUT
        'Field offset 32 bit machine 4
        '64 bit machine 8
        <FieldOffset(0)> _
        Public type As Integer
        <FieldOffset(8)> _
        Public mi As MOUSEINPUT
        <FieldOffset(8)> _
        Public ki As KEYBDINPUT
        <FieldOffset(8)> _
        Public hi As HARDWAREINPUT
    End Structure

    Private Structure MOUSEINPUT
        Public dx As Integer
        Public dy As Integer
        Public mouseData As Integer
        Public dwFlags As Integer
        Public time As Integer
        Public dwExtraInfo As IntPtr
    End Structure

    Private Structure KEYBDINPUT
        Public wVk As Short
        Public wScan As Short
        Public dwFlags As Integer
        Public time As Integer
        Public dwExtraInfo As IntPtr
    End Structure

    Private Structure HARDWAREINPUT
        Public uMsg As Integer
        Public wParamL As Short
        Public wParamH As Short
    End Structure

      Public Shared Sub SendKey(ByVal key As Char)
        Dim Inpts(1) As INPUT

        'key down
        Inpts(0).type = 1
        Inpts(0).ki.wVk = Convert.ToInt16(CChar(key))
        Inpts(0).ki.dwFlags = KeyDown

        'key up
        Inpts(1).type = 1
        Inpts(1).ki.wVk = Convert.ToInt16(CChar(key))
        Inpts(1).ki.dwFlags = KeyUp

        SendInput(2, Inpts, Marshal.SizeOf(GetType(INPUT)))
    End Sub
End Class

Описание событий клавиатуры
   Private Type KEYBDINPUT
       wVk As Integer
       wScan As Integer
       dwFlags As LongPtr
       time As LongPtr
       dwExtraInfo As LongPtr
       dummy1 As Long
       dummy2 As Long
   End Type

   Private Type INPUT_TYPE
      dwType As Long
      dummy As Long  
      ki As KEYBDINPUT   'сдвинул на Long*2
   end Type

Описание событий клавиатуры
-------------------------------------------------
    Private Type MOUSEINPUT
        dX As Long
        dY As Long
        mouseData As Long
        dwFlags As Long
        time As LongLong
        dwExtraInfo As LongPtr
    End Type

    Private Type INPUT_TYPE
        dwType As Long
        dummy As Long    
        mi As MOUSEINPUT   'сдвинул на Long*2
    End Type