the last time I used my iPhone is before about 5 months and now when I try to open it it won't turn on, I tried to press the home and sleep button but it didn't work.
iPhone 5s, iOS 9.2
Plug the device in to charge for a minimum of 1-2 hours, then try the home and sleep button. Was there a charge on the phone when you put it up? Also see this support document. If your iPhone, iPad, or iPod touch won't turn on or is frozen - Apple Support
Very possibly is. You did not answer my question about whether it had a charge on the battery when you stored it. It is very possible that you killed the battery. Make a Genius Bar appointment and have it checked.
It sounds like you probably need to charge your device...
I tried to put it for 5 hours, I talked to apple they said I have to come to the store because it look like there is a problem with the battery
I think it was about 2% when I shut it down, so do you think I will probably have to buy a new battery? and if I did, will I have to formate the phone?
The battery probably needs to be replaced, since you should charge the battery to about 50% before putting a device in storage. Your data may be intact, but I would hope you had a backup if not.
iPhone won‘t turn on
