How to sort a single column without disrupting the rest of the Column ?

Hopefully my question makes sense, I'm very tired and I've been fighting with sorting for awhile

Please help me
Code:
 range = sheet.Range("A1:D2000")
        range.Select()
        range.Sort(Key1:=range.Range("D1"), Order1:=Microsoft.Office.Interop.Excel.XlSortOrder.xlAscending, Orientation:=Microsoft.Office.Interop.Excel.XlSortOrientation.xlSortColumns)