iHTC ClockCal is a lockscreen theme featuring an HTC style (12 hour format) clock and a monthly calendar. There are a few backgrounds to choose from included. SSH to private/var/stash/themes/iHTC ClockCal open the "private" folder and choose the background you want. Rename it to Clock.png. There was a mix up in updates a few days ago. This should fix it if you want your calendar back!