Loop through folder and applying code to all xlsx - excel

Question

Had a code that was able to apply protect workbook but didn't save after running a different sub routine. I'm trying to apply a macro to all xlsx files in a folder where I'm deleting two sheets and applying a protect workbook. When I run it without the sheet deletion, the code runs but it doesn't apply to any of the files inside the folder.
Sub LoopThroughFilesFolder()
Dim StrFile As String, wb As Workbook, ws As Worksheet
StrFile = Dir("C:\Users\user\Documents\Destroy\*.xlsx*")
Do While Len(StrFile) > 0
For Each ws In Worksheets
If ws.Name = "Summary Copying" Or ws.Name = "Sum Totals" Then
Application.DisplayAlerts = False
ws.Delete
Application.DisplayAlerts = True
End If
Next
ProtectBookStructure ThisWorkbook, "password"
StrFile = Dir
Loop
End Sub
Fixed with this code
Sub LoopThroughFilesFolder()
Dim myfile As String
Dim wb As Workbook, ws As Worksheet
Application.ScreenUpdating = False
myfile = Dir("C:\Users\user\Documents\Destroy\*.xlsx*")
Do While myfile <> ""
Set wb = Workbooks.Open(fileName:=myfile)
For Each ws In Worksheets
If ws.Name = "Summary Copying" Or ws.Name = "Sum Totals" Then
Application.DisplayAlerts = False
ws.Delete
Application.DisplayAlerts = True
End If
Next
ProtectBookStructure wb, "password"
wb.Close savechanges:=True
myfile = Dir
Loop
Application.ScreenUpdating = True
End Sub

Answer 1

I recommend you check out the link posted by #DecimalTurn as a comment to your question.
A solution for your problem may look like this:
Sub LoopThroughFilesFolder()
Dim strFile As String, wb As Workbook, ws As Worksheet
strFile = Dir("C:\Users\user\Documents\Destroy\*.xlsx")
Do While Len(strFile) > 0
'Open the workbooks like this:
Set wb = Application.Workbooks.Open(strFile, False, False)
'In the following, use the "wb" variable to do what you want for the
'opened workbook.
For Each ws In wb.Worksheets
If ws.name = "Summary Copying" Or ws.name = "Sum Totals" Then
Application.DisplayAlerts = False
ws.DELETE
Application.DisplayAlerts = True
End If
Next
ProtectBookStructure wb, "password"
'Save and close
wb.Close SaveChanges:=True
strFile = Dir
Loop
End Sub
This code may still not work depending on how ProtectBookStructure looks like or if any of the workbooks in the folder are already password protected.