Why does my phone delete stuff when it dies

I have a HTC one m8 and it died and when i charged it and turned it back on it logged me out of my wifi, my facebook, my gmail and my lock screen wasnt working until i restarted it in the settings and restarted my phone... my brother aslo has a HTC onem9 and when his died his contacts got delete!!! I never had this problem or heard of the phones doing this sooo whyy

from Android Forums at AndroidCentral.com - Ask a Question http://ift.tt/28QRMaS
via IFTTT