Hi Rani,

very likely this isn't possible at all,
if there are automatic linebreaks.

If there are manual linebreaks,
then strictly speaking, it is impossible
even in theory, as the linebreak is a part of the line.
You wold have to insert your text *immediately before*
the line's end.

Which may result in a new different automatic linebreak,
and increase the number of lines of the doc.

You may play a bit with the following,
just to see, why it doesn't work.

Sub Macro3()
Dim lngL As Long
Dim lngC As Long
ActiveDocument.Range(0, 0).Select
selection.ExtendMode = False
lngL = ActiveDocument.BuiltInDocumentProperties("Number of lines")
For lngC = 1 To lngL
  selection.GoTo what:=wdGoToLine, _
  which:=wdGoToAbsolute, _
  Count:=lngC
  selection.Bookmarks("\line").Range.InsertBefore "yyyy"
  selection.Bookmarks("\line").Range.InsertAfter = "xxxx"
Next
End Sub

That is going to really screw up the present line breaks.  When you add the
"line break start" at the beginning of the line, some of the text that was
towards the end of the line will wordwrap onto the next line.