I forgot my passcode and I dont know how to get back into my phone?!

So me and my dad share a charger and he went on a trip out of state and took the charger with him. I didnt want to buy a new charger since im getting a new phone anyways and so I decided to just wait to charge my phone when he got back. That lasted a week and I TOTALLY forgot my passcode! I have went on Youtube and looked but they said if I do what they do I will loose all my stuff on my iphone! So how do I unlock it without deleting everything? -Zoe