How to recover music after restoring my iPhone 4s? - 1

It started when I tried to download a new song and iTunes said it can't read my iPhone. It's not the first me it did that. It worked fine the day before & I was downloading music too. So I restored it to factory settings. I backed it up but I chose to restore from back up but all my apps/music/photos are wiped from my phone. How do I recover my music? I tried to sync it many times but it doesn't come back. I are the music on my music bar for the iPhone but the songs are not clickable. Only
The music bar for iTunes library is clickable. I really want my music back!

ITunes won't let me transfer music from?

I erased & synced on a friends comp so all her music is on my iphone. My assumption was that the original comp my iphone was synced to would just let me re-enter its music onto my iphone but it doesn't. So I authorized my comp so it would 'transfer purchases from my phone' (an option in the file menu) and it said it was successful but the music doesn't show up in my itunes music. Any ideas on what went wrong?

Stright talk on an iPhone 3gs?

I was looking for a way to have an iPhone while using Straight talk service (45$ plan) I have noticed a lot of people using unlocked iPhone 4s… Is it possible to use a normal AT&T iPhone 3gs?

Viber doesn't tag all my contacts?

I got Viber a long time ago (iPhone 4S, and it works fine). Recently I got Viber for my sister (iPhone 3G) and my mum (iPhone 4S).

My sister can see mum who is on viber but she can't see me.
I can't see my mum or my sister
My mum can't see me

We see other people on our contacts who is with viber but not each other

I turned off the phones and tried again but still nothing
I double pressed the home button on the home page and cleared all the apps at the bottom, but still nothing

What is wrong and how can I fix it?

I threw my iPhone 3gs and it won't turn on

I have tried almost everything and when people say to connect to itunes it doesn't pop up. And when I press the lock and home button it won't turn on. And I have been charging it! Anything helps, thanks!