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)]

Try:

Sub test()
Dim ff As Integer: ff = FreeFile
Dim lines() As String, i As Long

'here the code for filename and RandomNum 

Open filename For Input As #ff
    lines = Split(Input(LOF(ff), #ff), vbNewLine)
Close #ff

MsgBox "line " & RandomNum & " is " & lines(RandomNum -1)

'of course instead of just msgbox you can process it as you wish
' note it RandomNum - 1 , because lines() are numbered from 0

End Sub

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1. Have you tried it? It works. How? Whole file is read into array then closed. After that only needed array element is presented. It is much quicker than reading line by line.
2. Code Tags!!! It's final kind reminder.

1) Not really. Use square closing bracket - can't you see the difference?

2) I don't think you tested my solution at all - IMHO shall be fine for (almost) any computer and file (20 000+ rows and 100+ characters is not a big deal - just few MB).
So I'm a bit disappointed.
But if you do not trust, of course you can read this "snail method" line by line.
Something like:

Application.ScreenUpdating = False
dim my_Data as string, j as long
for j=1 to RandomNum
  Line Input #1, my_Data
next j
For i = 1 To 81
Char = Mid(my_Data, i, 1)
If Char <> Chr(34) Then
Rng.Cells(i) = Char
End If
Next i
Close #1

Shall do. In real life you shall also test if your RAndomNum is not out of the last line of the file.