Create a cell with the password you need and name it "GetThePassword". Then
try the code below. You should be able to adapt it to suit your needs.

'Make workbook ready for development
'
Sub StartDevelopment()

Dim mySheet As Worksheet
Dim Password As String

   ' read the password from the named range
   Password = [GetThePassword]

   'check password
   If UCase(InputBox("Password: ")) <> UCase(Password) Then
       MsgBox "Wrong password.", vbOKOnly + vbCritical, "Sorry..."
       Exit Sub
   End If

   'unprotect the workbook, and then all the sheets
   ActiveWorkbook.Unprotect (Password)
   For Each mySheet In Sheets
       With mySheet
           .Unprotect (Password) 'unprotect the sheet
           .Visible = xlSheetVisible 'unhide the sheet
       End With
   Next

End Sub