Hard luck man. I would also be frustrated to know just one day that my flagship phone died on me. I would also be frustrated to know that Samsung has a 2 year software update policy lolDo check if you battery died. Just in case
That's tough. I mean, you can retrieve your contacts from your sim. Better hope you made the switch to OneDrive in Gallery, or check Google Photos to retrieve your photos/videos. Alternatively, maybe you made a SmartSwitch backup?