You need to reset the calendar view of MS Outlook by the using of reset view option. I hope it will be helpful for you.
Launch Microsoft Outlook.
Click “Calendar” under “My Calendars” in the left-hand navigation pane.
Click the “View” tab in the main program menu.
Click “Change View” in the “Current View” group.
Click “List.” This displays a list of all your calendar items in the main program pane.
Click anywhere in the item list. Press the “Ctrl” and “A” button on your computer keyboard. This selects all items in the calendar list.
Press the “Delete” button on your computer keyboard. This resets the calendar by deleting all items.
Thanks & Regards