Is there any way to retrieve a deleted single flight list? Please help.  

Flight information is stored in three places that I know of:

• The TXT files on your mobile device.
• The DAT files on your Mavic's internal card.
• The DJI servers when you sync your mobile device information.
  

The first ones (TXT files) can be deleted by uninstalling the app from your mobile device, but as far as I know there's no way to delete any of the other two types of log.