Hello MVZTX,
If you're unable to see calendar events you have created, you'll want to make sure whatever calendar you have them saved in is currently set to show. In the Calendar app, select Calendars at the bottom, then make sure the calendar you have the events stored in is checked.
Create and edit events in Calendar on iPhone
If the missing items were stored in iCloud, you can also try recovering them with these steps:
1. On iCloud.com, click
in the toolbar, then click Data Recovery.
2. Click Restore Calendars.
Available versions are listed by the date and time they were archived.
3. To the right of the version you want to restore, click Restore.
There may be more versions than can be displayed. Scroll to see them all.
Note: Wait until iCloud finishes restoring your calendars before you change them. During the restore process, any changes you make aren’t saved.
Restore your calendars and events on iCloud.com
On a side note, you should never allow someone else to use your Apple ID. An Apple ID account is intended as an individual account. If someone else is using your Apple ID, you run the risk of your personal data being merged or deleted by them.
How to create a new Apple ID
Cheers!