1976 (C3) clock problem

The clock on my 1976 Corvette was working well, but I had to disconnect the battery on the car for about a week.  When I connected the battery again I saw the clock had stopped working.  I tried connecting and disconnecting the battery a couple of times, but could not get the clock to start again.  Has anyone had similar experience?  Any suggestions?  Please let me know.  Thanks

|UPDATED|6/29/2021 7:33:39 AM (AZT)|/UPDATED|