MSCAL.OCX is the Microsoft Calendar Control. It hasn't been included in Access 2010 and later versions.
Hold down the (left) Shift key while opening the database. You should then be able to find the form(s) with the calendar control.
You'll have to remove this control and replace it with a text box. If the text box is formatted as a date, Access will display a small popup calendar next to the text box if it has the focus.
Depending on how the calendar control was used, you may have to modify the VBA code of the form to work with the text box instead of the calendar control.