Q: My i phone 4s will not sync calendars with my PC.

My i phone 4s failed to sync calendars with my PC, via i tunes, yesterday.  I have tried restoring the phone without success and in the process wiped my calendar completely.  The sync function seem to work on other categories, but will not sync with the calendar.  I've activated all calendars again without success, ticked all the appropriate boxes and still no information regarding appointments is transferred.  Could any please assist?