Hi Dilani,
Assuming it's a delimited file, you can't edit it "in place". Instead,
create a new file and copy the old one line by line until you come to
the line in question; then write the new line; and finally write the
remainder of the file.
This untested air code should get you started:
Dim lngFIn As Long, lngFOut As Long
Dim strLine As String
Dim strFName As String
Dim strTempName As String
Dim strFindLine As String
Dim strReplLine As String
strFName = "D:\Folder\File.txt"
strTempName = "D:Folder\File.$$$"
strFindLine = "Find Me"
strReplLine = "New Line"
lngFIn = FreeFile()
lngFOut = FreeFile()
Open strFName For Input As #lngFIn
Open strTempName For Output As #lngFOut
Do
Line Input #lngFIn, strLine
If strLine = strFindLine Then
Print #lngFOut, strReplLine
Else
Print #lngFOut, strLine
End If
Loop Until EOF(#lngFIn)
Close #lngFIn
Close #lngFOut
Kill strFName
Name strTempName As StrFName
