Private Sub Command5_Click()
      Dim TimeArray(1) As SYSTEMTIME
      Dim result As Long
 
      ' Define first element of SYSTEMTIME Array to be minimum date.
      TimeArray(0).wDay = 1
      TimeArray(0).wMonth = 1
      TimeArray(0).wYear = 2019
 
      ' Define second element of SYSTEMTIME Array to be maximum date.
      TimeArray(1).wDay = 31
      TimeArray(1).wMonth = 12
      TimeArray(1).wYear = 2019
 
      ' Call API to send message to control to set MinDate and MaxDate.
      result = SendMessage(Me.DTPicker1.hwnd, DTM_SETRANGE, _
         GDTR_MIN + GDTR_MAX, TimeArray(0))
   End Sub

Option Explicit
 
Public Type SYSTEMTIME
   wYear As Integer
   wMonth As Integer
   wDayOfWeek As Integer
   wDay As Integer
   wHour As Integer
   wMinute As Integer
   wSecond As Integer
   wMilliseconds As Integer
End Type
 
Public Declare Function SendMessage Lib "user32" Alias _
   "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, _
   ByVal wParam As Long, lParam As Any) As Long
 
Public Const DTM_SETRANGE = &H1004&
Public Const GDTR_MIN = 1
Public Const GDTR_MAX = 2

Vielen Dank an alle in diesem Forum, welche mir Ihre Zeit schenken und sich mit meinen Problemen befassen! Ich weiß das ernsthaft zu schätzen und danke allen, die sich mit dieser Frage befassen herzlich!!!