Hi and welcome to G4EF

So, you want all txt files to be open simultaneously, right ?

This is an easy task and can be done in any language. But I will prefer VBScript as you need not compile it and you can directly run it like a batch file.

Code: VB
Dim objFSO
Dim MyFile
Dim MyFolder
Dim objShell

Set objFSO = CreateObject("Scripting.FileSystemObject")
Set MyFolder = objFSO.GetFolder("C:\Test")
Set objShell = WScript.CreateObject("WScript.Shell")

For Each MyFile In MyFolder.Files
    If Right(MyFile.Path,4) = ".txt" Then
        objShell.Run("notepad " + MyFile.Path)
    End If
Next
Copy the code above, paste it in notepad and save the file as "Test.vbs". Run it .. it will work

The code is quite self explanatory, so you won't have difficulty understanding it. If you need to change the target folder, change the variable MyFolder.