stuck on the apple logo

my Iphone 5s is stuck on the apple logo, i tried pressing on the home and start button but it didn't worked, after about an hour my phone turned off and said there wasn't anymore batterie i've charged my phone and 5minutes later, back on the apple logo and nothing was happening. What am I supposed to do ? i don't want to reset everything on my phone cause it's been a long time i haven't synchronized it with my computer and i have a lot of things in it, please someone help me.