Some folders inside Documents folder have suddenly disappeared

Hi,

I have a Dell Inspiron 15 2in1 touchscreen laptop Intel core i7 12GB memory 512GB SSD bought in 2017.

Yesterday while working normally I noticed that the majority of my folders inside Documents folder have disappeared. I didn't delete or move them. I searched for it everywhere in my laptop but no signs of it and I have also noticed that I have 145 extra GB available in my memory....so seems that they were deleted. How could this happened? I run an antivirus and didn't find anything. I also checked if the disk was working fine which it is. I have no explanation for this. 

Now I am trying using a recovering software but I after recovering them and trying to open each file, they seem to be somehow broken so I can't see them.

Can this be related to any software update?

Any idea on how to recover my files?

Regards,

Mai