Handling multiple sheet simultaneously is too much challenging and complex task for anybody. Considering this point, Excel is powered with hide and unhide functionality which helps end user to make visible required sheets for data manipulation. But, excel has a limitation to unhide multiple sheets at a single go. Thus, it becomes a very tedious and time consuming task to unhide multiple sheets in single attempt.

Can we unhide all hidden excel sheets at single attempt?and the answers is "Yes".

Here is the code which will make this task very simple.

Sub Unhide_ALL_Sheets()
' Author: Dreams24
' Written for VBA Tricks and tips blog
' https://www.vbatricksntips.com

Dim i As Integer
    For i = 1 To ThisWorkbook.Sheets.Count
        ' You can insert your customized if condition here to unhide specific excel sheet
      If Sheets(i).Visible = False Then
          Sheets(i).Visible = xlSheetVisible
      End If
    Next i
End Sub

Please refer Downloads to get Hide/Unhide add_ins.