The built-in Reminders app in iPhone works a lot for us. For instance, make daily schedule, set alarm for important business meetings or appointments, write down your shopping list, etc. However, if your important reminders on iPhone disappeared due to some reasons such as accidental deletion, iOS upgrade failure, virus attack, etc, what would you do? How to retrieve deleted or lost reminders on iPhone? In this post, we will give you 4 possible solutions to help you out. Read on and learn more details.