How to Update Particular Line in a textfile

txtFilePath= "C:\copy.txt"
txtRowNumber=3 '
TextToAdd="three"
 
Set fso= CreateObject( "scripting.filesystemobject")
Set f=fso.OpenTextFile( txtFilePath, 1)
txtData=f.readall
f.close
 
Set f=fso.OpenTextFile( txtFilePath, 2)
 
strTxtData=split( txtData,vbnewline)
 
For cnt=0 to ubound(strTxtData)
 
 
If cnt<>txtRowNumber- 1 Then
    f.writeline( strTxtData( cnt))
else
    f.writeline( TextToAdd )
End If
 
Next
 
f.close