how i backup deleted pdf files

Hi @Manish22095571u5do , 

 
Thank you for posting your query here. Could you help me with few details to understand your issue better? 

1. Have you deleted it from your device or from the application? 
2. Make and model of your device? 

Try to sign in to Adobe Reader with the same Adobe account on which you had data.  

If you are not uploading the files to Adobe Document Cloud or saving it to any other location, then the files will be deleted permanently. 

It is not possible to retrieve the files once deleted directly from the application. 

I would suggest you always save a copy of the file to some other location or you can upload the files to Document Cloud. 

If the files were saved within the application, they are by default uploaded to Document Cloud. 

To check your document cloud:Adobe Document Cloud.  

Otherwise, there's not much we can do to recover those files for you.  

 
For more help refer to: https://helpx.adobe.com/acrobat/mobile-app-faq.html 

Let me know how it works at your end. If you have any further queries please feel free to reach. 

Regards 

Ria