Salesforce archives activities to save storage space. If you cannot view notes, activities, or anything else, view archived activities.
• Events that ended more than 365 days ago
• Closed tasks due more than 365 days ago
• Closed tasks created more than 365 days ago (if they have no due date)
Salesforce doesn’t delete archived activities, but you do have the ability to manually delete them.
In the activity timeline, open the More Past Activity dropdown, and select View All.
The archived activities will appear in a new tab.
Please note - You can reach out to Salesforce Support to extend the 365 day limit for activities to the Maximum limit of 2555
Recommended maximum - 1825 days (5 years) maximum