Losing info for Reminders

Hey there ntphan,

I have an article for you that will help you troubleshoot this issue with your Reminders on your iPhone:

iCloud: Troubleshooting iCloud Reminders and Tasks

http://support.apple.com/kb/TS4000

Troubleshooting Reminders on iOS devices

If you're having trouble with Reminders on an iOS device (iPhone, iPad, or iPod touch) and iCloud Calendar, try each of these steps, testing after each to see if the issue is resolved:

• Make sure that you're using iOS 5 or later. If you meet these requirements but your issue continues, tryinstalling the latest version of iOS supported by your device.
• Make sure that your iCloud account is configured correctly in Settings. For instructions on setting up iOS for iCloud, see iCloud Setup. Reminders is a separate data type on iOS. It must be enabled via the Reminders setting in Settings > iCloud.
• Make sure your iOS device is online. Attempt to view www.apple.com. If you can't connect to the Internet, your iCloud Reminders will not update in Calendar. Learn about troubleshooting your Internet connection.
• Open a secure website to test if ports 80 and 443 are accessible. Reminders requires port 443 access to iCloud to push and fetch updates to and from the iCloud Calendar and Reminders servers.
• If recent changes don't appear in Reminders, try forcing a refresh. In iOS 7:
  • Open the Calendar app.
  • Tap the Calendars tab to load the Calendars list.
  • Pull down on the list to refresh both calendar events and reminders.
• If recent changes simply don't appear in Reminders, try forcing a refresh. In iOS 6 and 5:
  • Open the Calendar app.
  • Tap Calendars in the top-left corner to load the Calendars list.
  • Tap the Refresh button in the lower-left of the Calendars list.
• Quit and restart the Reminders app on your iOS device.
  1. In iOS 7, press the Home button.
  2. Press the Home button twice to see preview screens of the apps you have open.
  3. Find the Reminders preview screen and swipe it up and out of preview to quit the application.
• Quit and restart the Reminders app on your iOS device.
  1. In iOS 6 and iOS 5, press the Home button.
  2. Press the Home button twice to open the multitasking menu.
  3. Press and hold the Reminders icon until it jiggles.
  4. Tap the red circle in the upper-left corner to quit the app.
  5. Press the Home button to get back to your Home screen. Wait a minute before reopening the Calendar app.
• Change the Sync settings for your calendars:
  1. In iOS 7 and iOS 6, tap Settings > Reminders.
  2. In iOS 5, tap Settings > Mail, Contacts, Calendars, then scroll down to the bottom to the Reminders section.
  3. TapSync. If Sync is set to All Reminders, set it to a specific duration, such as Reminders 1 Month Back. If it's already set to a specific duration, set it to All Reminders.
  4. Wait several minutes and refresh again, as described previously. Then open the Reminders app again.
• Turn iCloud Reminders off and back on:
  1. Tap Settings > iCloud.
  2. Turn off Reminders. Choose to delete data only if your reminders exist at icloud.com/#reminders and on one or more of your devices. Otherwise, choose Keep Data.
  3. Wait a few minutes before turning Reminders back on.
• Restart your iOS device: Hold down the Sleep/Wake button until the red slider appears, then drag the slider. After the device turns off, turn it back on by pressing the Sleep/Wake button until the Apple logo appears. This may sound simple, but it reinitializes your network and application settings and can frequently resolve issues.

Thanks for coming to the Apple Support Communities!

Cheers,

Braden

You're welcome, ntphan!

-Braden