Use this code to find specific word in text file
Dim InputStr As String = TextBox1.Text
For Each FileStr As String In IO.Directory.GetFiles("C:\your folder", "*.txt")
If IO.File.ReadAllText(FileStr).IndexOf(InputStr) >= 0 Then
ListBox1.Items.Add(IO.Path.GetFileName(FileStr))
End If
Next
Thanks
SP