Hi Jennifer, 

Welcome to Box Community and glad to help!

As for your critical files that disappeared, you may check the following: 

• Identify the ownership of these files. Are these your owned files or just collaborated with? If it's the latter, please contact the owner. 


• For your owned files, please checkout your trash/bin icon. It's where you could restore the deleted files that you own. 

To restore or permanently delete specific items in Trash:

The steps below apply whether you’re selecting from search results or from all Trash items.

1. Hover to highlight the row of the item you want. The More Options ellipsis (…) displays.


2. Click the ellipsis (...).  Then: 

• To return the item to its original location in Box, click Restore.

3. At the prompt, click Okay.

Hope it helps!