I have no idea why the code you have used previously no longer works for you (it doesn't work here), but adding file selector is easy enough
Code:
Dim oRng As Range
Dim oShp As InlineShape
Dim sName As String
Dim lngWidth As Long
Dim fDialog As FileDialog
Set fDialog = Application.FileDialog(msoFileDialogFilePicker)
With fDialog
.Title = "Select the image to insert"
.InitialFileName = Environ("USERPROFILE") & Chr(92) & "Pictures"
.AllowMultiSelect = False
.Filters.Clear
.Filters.Add "Graphics Files", "*.jpg,*.png,*.gif, *.bmp, *.tif"
.InitialView = msoFileDialogViewList
If Not .Show = -1 Then Exit Sub
sName = fDialog.SelectedItems.Item(1)
End With
Set oRng = Selection.InlineShapes(1).Range
lngWidth = Selection.InlineShapes(1).Width
oRng.Text = ""
Set oShp = oRng.InlineShapes.AddPicture(sName)
oShp.LockAspectRatio = msoTrue
oShp.Width = lngWidth