My phone won't turn on at all, stuck in downloading mode, dead battery

Well so yesterday I was using my phone as usual only difference was that battery was almost drained. Then, I accidentally accessed downloading mode and from there I couldn't do anything.. So I tried to charge it over night and turn it on again dozen times with different combinations but every time is gets to downloading os where it tells me to press vol up to continue and vol down to restart, after pressing down it gets into Samsung logo screen and turn itself off and now I can't turn it on at all. Doesn't react to charger. Sometimes it turns on, getting into download mode and turn back off.. I'm afraid I might loose all data is there any help?

EDIT: The problem is that my battery is dead and it refuses to charge because it is turned on on downloading mode..Sometimes when i press vol down, power button, home button it shows download os and if i hit vol down again ill get downloading mode on screen than it turn itself off.