When creating your wallet, you have been prompted to save the PDF document which is your backup recovery document. This document is generated directly in your browser and never shared with BTC.com. Each user has to confirm that they securely stored their backup PDF. The PDF can not be regenerated again afterwards.
BTC.com never sees your backup PDF, therefore only the user has this document.
Possible locations for the PDF file:
If you signed up on the web page you have Downloaded your backup PDF to your computer and perhaps even printed it out. Look in all your Download folders and think of which device you used to create your wallet on.
If you have signed up via the mobile BTC.com wallet app, check your email inbox if you have sent yourself the backup PDF.
If you signed up using an iOS device, you can check Dropbox, iCloud, iBooks as possible backup locations.
If you chose to store your backup PDF on the phone as well:
* On Android, check the app folder for the BTC.com wallet app on your filesystem
* On iOS, use 'iTunes Filesharing' to access your backup PDF through iTunes if available