How long can I store DIY canned/sterilized bottled food before they go bad?

If the home canning is done properly (by following established standard practices as described in USDA publications or Ball Blue Book, for example), the food will last for many years without "going bad" in the sense of becoming unsafe to eat. It will, however, deteriorate in quality during that time. This depends to some extent on how it is stored, too. Canned peaches that are kept in the bright light of a windowsill will darken noticeably within months; it will develop off flavors as well. Stored in a cool dark place, a jar of peaches from the same batch could still taste fresh after a couple of years.