Casually at first, then more frantically, I began to check the site. I entered an old page URL and there was a standard 404 page not found message. I asked for the FTP and administrative login information but they hadn't been given any. So, I made phone calls and fired off email but received no response for three long days. By the time the fixes were made and the site was functional, it had been dropped from the search engines, email had bounced for a week, customers were lost forever.
Traffic is practically nonexistent now.
The site is no longer busy or productive. The owners are no longer prosperous or joyous. A redesign doesn't have to kill a site. Don't let a similar tragedy happen to you. Rebuild with care, caution, and consideration.