By default, your android calendar will synchronize:
- somewhere around 30-50 days in the past (i’m not exactly sure)
- all future items
- all recurring items
This means: when you start with a new phone or did a full wipe of your phone, you’ve lost all your history beyond 30-50 days. The only way to see these appointments is to log in to your web calendar.
To sync an old item, you could “refresh” the old items (say, edit some fields like location or time) but you don’t want to do that for thousands of items.
There is a way to “refresh” all your items at once:
- Log in to Google Calendar via the web
- Go to “Settings -> Calendar Settings” at the top
- Go to the “Calendars” tab
- at the bottom, next to “Create new calendar” you will find “Import Calendar” and “Export Calendars”
- Export your calendar and save the .zip to some place on your harddisk
- Unzip the .zip, you’ll get an .ics file
- Now choose Import Calendar and select the .ics file
- Your calendar will be overwritten with a backup of itself. No duplicates will be made (don’t worry)
- Your phone will notice all the “new” items and will download your entire calendar