Directory Looping Copying And Pasting

In my very crude code below....I would like to speed up the coding so by extracting data from some 800 CLOSED workbooks and pasting the data from Non-contiquous cells in an active workbook on one sheet. Can't seem to ge the = Excelmacro4 closed workbooks method to work so I went with opening each workbook, extracting data and then closing each workbook...way too slow.

Question 2. As the loop progresses...I would like to concatenate the text strings copied from the Source books Ranges G4 and G5 as they are pasted into a single cell in the destination workbook. Can't figure out how to either concatenate or xlpaste special in the coding.

Question 3. IF a user has a one of the workbooks OPEN, how do I copy that data as well other than On Error Resume Next?

Dim wbOpen As Workbook
Dim wbDest As Workbook
Dim WS As Worksheet
Dim i As Long
Sub GetdaData()
Application.ScreenUpdating = False
Application.EnableEvents = False