Creating A Link To The .pdf File

I have some code that looks at the part # in column D and then goes out to the D drive to drawings (.pdf files) and creates a hyperlink.

The problem is that it is only creating a link to the .pdf file and not to folders. I need a hyperlink to the folder so when it is clicked the open folder pops up and shows the multiple files associated with that part.

Link should be the same regardless of file or folder, no? As long as the name matches link should be made, correct?

E.g.
123-100.pdf (column D part #) links to 123-100.pdf file on CD
456-200 (folder name in column D) no link created to folder named 456-200 on CD.

Sub Hyper()
MyPath = "D:"
StartRow = 2
EndRow = 20

x = 0

For i = StartRow To EndRow

Cells(i, 4).Select

MyFileName = ""
MyFileName = Dir(MyPath & Cells(i, 4).Text, vbNormal)

If MyFileName "" Then
x = x + 1
Cells(i, 4).Select
ActiveSheet.Hyperlinks.Add Anchor:=Selection, Address:="D:" & MyFileName
End If
Next i
End Sub