Can't find deleted files

Hi Matt, 

Welcome to Box Community and glad to assist! 

Notes:

• When items are deleted from a collaboration folder, both the owner and the person who deleted the item can recover the items from the Trash. 
• If you are removed as a collaborator from a file or folder that you've deleted, you no longer see that item in Trash. To see the item in Trash, you must be again added as a collaborator to that item.

If you have trouble finding your deleted file, try the filter and search functions in trash. 

• To search to through trash: 

1. Navigate to your Trash folder.
2. Toward the top, click the Search Files and Folders
3. In the box that displays, enter any search parameters.
4. Check Only search inside of “Trash.”
5. Press Enter.

• You can also use filters such as "Items I own," "Items I deleted"

For more details, please see this article. 

Hope it helps!