Iphone 4 wont turn on

So me and my sister used to use the same iphone (iphone 4) but now that she bought an iphone 5s i took the iphone 4. A few months ago a notification on our phone came up and asked if we wanted to update ios 7 but my sister said no se she canceld it. Today i wanted to update it so i went to setting-general-software update but nothing would come up. so i searched in the app store for any app to update ios 7 but nothing would come up either, thats why i installed an app which helped people understand how to use ios 7 and i think it also helped you to update it so thats why i installed it. while i was waiting for it to install i was chatting with my friend on an app but my phone turned off. i thought it needed to charge so i putted in the charger and when i turned it on it would turn on but a page saying:'connect your phone to itunes' came up and there was no way to remove the page so thats why i took of my charger to put it on my pc but when i took my wall charger off the phone turned off , but anyways i putted the charger on my pc but it wouldnt turn on! it would open at the black screen with the apple logo.so i searched on google and i saw a comment saying :

Please follow directions in this Apple article:

http://support.apple.com/kb/HT1808

and i did so. i was waiting for it to restore and i turned my head away for a minute and when i turned it back i saw that it was finished and i tried to turn on my phone but it wouldnt and then i read that i should wait 15 and it will turn on by itself but it didnt so i tried to restore it again but this came out :The iphone could not be restored. an unkown error occurred (11). i tried it again and the same thing happened! i dont know what to do ! if i put my iphone to charge in a wall charger the furthest it could go is at the page where it says to connect it with itunes and the second i remove my charger it turns off and when i connect it with the pc charger the furthest it can go is at the black screen showing a charger and the itunes logo !! 😟 please help me, i really need my phone

by the way the button up on every iphone ( some people call it sleep/wake button ) doesnt work , so even when my phone worked it used to lock itself after 1 minute without me using it . i use the home button to turn on and off my phone.