My sim card its not working

I hope someone can help me.
I have iPhone 4 and I updated it with the newest version 5.1 so now my sim card its not working. NO SERVICE. So now i can't text and call!

Why has my Iphone 4 used so much data?

I'm on a Virgin mobile plan and I've been given 2GB data allowance per month. I've never used even 1GB of it before, and then suddenly I got a text from Virgin saying I'd gone over my 2GB by 1.7GB! So I managed to use 3.7GB in less than a month. I had a ridiculous bill, I'm not doing anything different at All but I've checked my data usage and I've used almost 900MB in 5 days.

Please help me! I can't afford to go over again! I've turned off all my internet and location services so I don't risk going over, but this has never happened to me before and I really want to know what's going on.

Getting a iPhone 4s need the best carrier?

Ganna get a iPhone 4s need the best sevice company people told me sprint Verizon and AT&T Are the top 3 and I wanna know witch is the best and is it better to buy the iPhone 4s at apple best buy or the best sevice carrier

Nike + Running App - won't sync?

Ok, I've used the app about a dozen times and it's great, but I smashed my iPhone and got a new one. Nike + didn't sync so I had to log in again but I've got two problems:

1. Whenever I try to sync or login, it shuts down

2. Only some of my data, 1 one piece of it rather, syncs (the amount of NikeFuel) - the important stuff like my dimensions and running data are missing. The thing is, they are still on the Internet in my online Nike + account.

What the heck is going on? Anyone help?

I cracked my iPhone 4s Screen?

I dropped it and the screen cracked all over. It still works perfectly fine but it looks terrible. I don't want to go to the Apple store because they charge so much money.
Does anyone know any replacement kits that aren't too expensive. If so, I'd really appreciate it!

I'm trying to take the sim card out of my Iphone 4s?

I'm trying to sell my iphone 4s. I already took out the sim card, and everything. Now when I turn it on, it still has my service. How can I uninstall the service? Because I can't cancel my service because I have a contract, I just can't afford a new phone. So I'm selling my iphone because I can go with out a phone for a while. I don't want to sell the iphone with my service in it, no way. I even factory reset the iphone and everything. It still has my service in the corner. Please help me, I'm trying to sell this as soon as possible for my school books. Please please please!

Added (1). I even tested it when I turned it back on, I can still make calls. Receive texts and everything. So please don't say I can't because I've picked up my phone to a phone call. & received many texts.