Private Function ZeileLesen(sDateiPfad As String, lZeile As Long) As String
    Const sStart As String = "[start]"
    Const sEnde As String = "[ende]"
    '--
    Dim iFF As Integer
    Dim sZeile As String
    Dim lZaehler As Long
    Dim StartPosition As Long
    Dim EndPosition As Long
    '--
    iFF = FreeFile
    Open sDateiPfad For Input As #iFF
        Do Until EOF(iFF)
            lZaehler = lZaehler + 1
            Line Input #iFF, sZeile
            If lZaehler = lZeile Then Exit Do
        Loop
    Close #iFF
    '--
    StartPosition = InStr(1, sZeile, sStart, vbTextCompare) + Len(sStart)
    EndPosition = InStr(StartPosition, sZeile, sEnde, vbTextCompare)
    '--
    ZeileLesen = Mid$(sZeile, StartPosition, EndPosition - StartPosition)
End Function

Private Sub Command1_Click()
    Text1.Text = ZeileLesen("C:\kk.txt", 1)
End Sub