Missing Events
For your security and privacy, your events are stored in your private iCloud account. If you turned off access for Days Since to access iCloud, the events that you put into your iCloud account will no longer appear. Although you are not required to use iCloud, it is recommended for backup and syncing between devices.
To restore your events, simply turn on iCloud access:
Open Settings
Tap on your name
Tap on iCloud
Locate iCloud Drive and ensure that is switched on.
Scroll down to Days Since and ensure that is switched on.
Note: Both iCloud Drive & Days Since need to be switched on.
Once iCloud is turned on, you can check the status of your events in iCloud:
Open Days Since
Tap on the gear in the upper left corner
Scroll down to the version number & tap on it three times
The status of your events will be displayed