A Big Problem!

At the yesterday , i chating with my freinds in messenger app and browsing facebook app .. like any one who do ! (the battery was 30%) .. but the problem after the battery was 0% the phone power off "like any android phone" then , i put it charging .. , i let it charged 12% and i powred on my phone at the first time the phone make me the default interface (put the fingerprint) and it will open the Main of apps ... at that time i turn on the wifi for starting the download is paused after the battery was 0% and for complet a message i don't compelted ... after i press the button of start the download the phone blocked and it transfer me at a anothe interface (no fingerprint / no apps / no app of security / no my images) every thing it transfer at guest mode i guess , i try to power the phone off or just restart it but it don't let me do it ! :/ , Please iFixiT i need your help , Please Help me ! :(