recover files on 6P after backup and reset.

after the OTA install of 7.0 I started to have issues with my 6P freezing many times in a day. FInally decided to do a backup and reset last week and phone has been running well again. Was warned about loss of data. Backed up my photos and documents. Completely forgot about a number of audio files recorded with the Smart Recorder app a few months back. Those audio files appear to be gone. I have seen some file recovery apps. Would I be able to recover those files with that type of software? Or might those audio files be somewhere in the backup (not sure what is really backed up in the backup and reset process) The recovery software requires rooting. I know the 6P allows for easy rooting but I'm not that technical and there is always a warning or a story of something bad happening. I don't care about rooting, and would not do it anyway but I would do a root if I could get the files back. And I would want to unroot later. Is the Nexus toolkit a good option for rooting and unrooting? Thanks for any help.