Text messages not being delivered on Iphone 4?

They were working just fine and tonight it's just not working. It always gets stuck towards the end and I get the 'not delivered message' I tried resetting my network settings, but it didn't help. How can I fix this?

IPhone 4 Black screen

IPhone 4 black screen and my phone lock button is spoiled! Help please!

Added (1). IPhone 4 stuck at black screen, like when you off your phone *

I switched iPhones, do I have to rebuy an app I paid for?

So, I got a new iPhone, but I haven't put the SIM card in yet because I'm waiting tomorrow to go and get it put in.

Basically I'm using it without my SIM card in it.
I went to download all my apps, and it says I have to rebuy this one app I've already bought.

Do I actually have to repay? Or is there a trick to this?
Was I supposed to transfer it or something from my SIM card?

So confused.

How to use my iPhone in Canada?

I have an AT&T iPhone 5 and it is unlocked. I'm only gonna be in Canada for week, and would like to know what's the best (preferably cheapest) way to get service up there? I just need a bit of data to use maps to get around and iMessage.