There is a ultrabook 'Lenovo IdeaPad U400' with Intel Smart Response Technology. Some days ago a user decided to upgrade Win 8.1 to Win 10 using Microsoft free upgrade way. Right after the first reboot main partition (containing system & user data) was disappeared. I believe it was created using some Lenovo software because BIOS doesn't have option to enable RAID mode.
So the question is how to effectively recover the user data? Obviously files left untouched on disks.