Why is watch dead even after new battery?

How can I fix two watches, both of which have not been used for about a year? The batteries were dead, but they still did not work even after replacing the batteries. Took them to a watch man who said "if batteries left in, watch then no good". Cannot really believe this as there was no apparent damage. Was he telling me the truth? How can these watches be revitalised, as they look great and I regret not being able to wear them? - H E L P please!