I tried downloading Cydia, and my iphone is stuck on the app?

I was downloading cydia (by Jay freeman), and i was going in and out of the app with no problem, then when i tried to go to the home screen it wouldnt let me. I can't lock my phone, or even turn it off. The screen is stuck on it but not frozen, cause i can scroll on the screen and if i hit the home button three times the options come up. Or if i hold down a link and when the options come up i press open, but it won't actually open it. I've had so many problems with this phone, but i've always managed to find some way to fix them. Its less than a year old. I also tried calling myself with another phone to try to open up a new screen but when it was about to go to voicemail a quick thing at the top pops up saying click to return to call then goes away. So the last thing i'm trying is to just leave it and hope it dies soon, but i don't know if that will even work. Is there anything else i can try and do?

Can I use my iphone in china?

I'm a US citizen I will be studying in Beijing over the summer for 6 weeks.
Will I be able to bring/use my iphone 4s?
Can I make calls to the US?
Can I text to the US?
Can I use it for Gmail or yahoo mail?
Can I browse the internet on it?

What are the advantages of mobile upgrades?

I don't have a credit rating and can't get a contract on my own name.

My boyfriend is due for an upgrade on a samsung ace on the network Three so he said I could upgrade to a better phone. However, when we went into the shop the woman didn't explain what an upgrade means for us. I would like the new xperia z or an iphone 4 or something but how would that work?
Do I choose a new plan for texts and stuff or do I keep the same one?
Will I get a disount on how much I pay or is it just the same as taking out a new contract?

How long will it take me to save up 800$?

I want the Iphone 5, My mom just got me the Samsung Galaxy Note 2 and i really am grateful but i want the Iphone 5 so i'm going to save up my money, I can't pawn my phone because it has a crack in the screen. I get paid 20 dollars a week and so i need to know how long it will take to save up 800 dollars, I will get extra each week if i work hard on chores which i will. I'm on Tmobile so the Iphone 5 will be on there april 12th and i thought someone said it was going to be 200 dollars but i guess it is going to cost 675 dollars and i'm saving extra for cases and to get out of my contract, Please Help!
Thank you!
By the way i'm 13 and please don't tell me i'm too young when i'm saving my own money!

IPhone 4S headphones problem?

Okay so I'm not sure how but I tried to plug my headphones into my iPhone the other day and found that it was pretty much impossible. Somehow, I must have dropped it a weird way or something, I have squished one side of the headphone jack so headphones don't fit anymore. Since my year warranty ended a couple months ago, I can't get it fixed until I goto Reno and get it fixed using my insurance from Verizon. I wouldn't have to if I found some headphones that connect through the charging part instead. I figure since I have a couple of itrips that only connect through the charging port that iCan play it through. So my question is, does anyone know where I can get some of these, or if they even exist?

I forgot my twitter password, and can't access my email

When i sign in, twitter said that the password is wrong, however, i don't remember which email i used. I already try 'forgot password' and check every emails that i have, but there's nothing. I have a feeling it's on my old yahoo email, and it's an old one, i don't remember the pass, i also tried forget pass, but it's not working, the hint for the alternative email doesn't match to any of my emails, and i can't answer the question they asked, i don't know what to do.so, can anyone please help me? I already tried open my histories, but it didn't help. I also protect my twitter, i can only open it in my twitter for iphone, echofon, ubersocial becus it signed in already before.please, anyone? Help me, thanks:"""".

Added (1). Also i tried forgot pass by my username, they said they send it to an gmail.com address, i have gmail, but i can't fine the email from twitter.

Sound on iPhone 4s won't work?

My iPhone 4s has this funny thing it does where she sound shuts itself off and won't turn back on. It's not that I accidentally turned on the mute button or anything, the sound just won't work no matter how much I desperately try. I turn the volume buttons up and down but where how much volume you've got is supposed to be on the screen is totally empty (if that makes sense).It does the same when I go to my music and play a song, the volume won't show, its just empty space. It just to be something it only did like once every to or three months but now it happens all the time. When I put in my headphones it suddenly works but then I take them out and it's just the same. Is there something wrong with my speakers? Need help, thanks in advance.

Is the iPhone 4 and iPhone 4s the same size?

I'm getting an iphone 4 soon and i found this awesome case but it's for the iphone 4s. I want to know if the sizes are the same and if the camera lenses are the same size so a hard case will fit it.