Deleted files recovery, root? Android 6.0.1

[Guest JaPanAt]

Greetings.

I have an italian version of the VSU6 and I accidentally deleted some files while exploring files in the settings -> storage & USB -> internal storage: after selecting all the files under "Other" I accidentally hit the recycle bin icon so it started deleting many of the files there and while I hadn't understood what was going on, the thing crashed stopping deleting everything, even tho some hundreds of megabytes are gone.

Since I didn't and now can't root the phone, everything I'm trying to do to recover the lost files are futile.

Can you help me recovering them?
Or at least root the phone, or even downgrade to lollipop 5.0.*.

Thanks.