Google Calendar Now Allows You to Recover Deleted Events
Google has added a new Trash feature to Google Calendar, so you can now bring back events that you accidentally deleted.
It works for both individual and recurring calendar events that have been deleted, and your own calendar, as well as other calendars for which you have edit rights. As shown in the image above, to access the calendar trash bin, click the drop-down arrow next to the calendar. You can also permanently delete items from your shopping cart.
This is rolling out over the next few days for Google Calendar on the web.
Recover Deleted Events in Google Web Calendar | Google Apps updates