Probably not. If you are still in the early stages of growing your sourdough starter it is completely normal for your starter to slow down and become quiet. Eventually, the activity should pick up again. If your starter doesn't perk back up and you are in the feeding once-a-day stage, try adding a little additional flour at the 12-hour mark. You could also try leaving the starter unfed for longer than 12 or 24 hours (depending upon what stage you are in). Wait to feed your starter again until it starts showing signs of activity. The only time you start completely over is if you see any signs of mold.