I tried changing it again to this but its still not working.

Now Im getting a Runtime Error 13 - Type Mismatch at the 9th line :
Rows(Cells(n, n).Value).Copy

Any ideas anyone?

Sheets("Sheet1").Select
n = Range("A1").Value
Windows("3.xls").Activate
With ThisWorkbook.Sheets("Sheet1")
.Unprotect "1234"
End With
Sheets("Sheet1").Select
n = n + 1
Rows(Cells(n, n).Value).Copy
With ThisWorkbook.Sheets("Sheet1")
.Protect "1234"
End With
Windows("73.xls").Activate
With ThisWorkbook.Sheets("DataIn").Rows("3:3")
.PasteSpecial _
Paste:=xlPasteValues, _
Operation:=xlNone, _
SkipBlanks:=False, _
Transpose:=False
End With