read a line from external text files on a random basis

the random number called "RandomNum" got claculated from the total number of lines in each file. Each line is of the same exact length. I wish to read a different line each time.
My issue is where to place that random number in my code? Every try it generate an error.

[Code)

    Open Filename For Input As #1
    If Err <> 0 Then
        MsgBox "Not found: " & Filename, vbCritical, "ERROR"
        Exit Sub
    End If
    r = 0
    c = 0
    txt = 0
    Application.ScreenUpdating = False
        Line Input #1 Data(RandomNum)   ' get the data on a random basis from the file
        For i = 1 To 81
            Char = Mid(Data, i, 1)
            If Char <> Chr(34) Then
                Rng.Cells(i) = Char
            End If
        Next i
    Close #1    ' #1 is the reference of the file
    Application.ScreenUpdating = True

[/Code)]