Today I logged into iCloud on my iMac but I only activated the Back to my Mac service. When I opened Calendar my entire calendar was gone. On the edit menu I clicked Undo and my calendar was gone but the spinning beachball of death appeared. Calendar just showed a message that said that calendar data cannot be saved and it crashed. My entire diary was deleted. I have a backup from about a month ago but there is very crucial information added in the past month that I need. I do not have a time machine backup of my computer. Is there any way I can get my calendar back?