So there's this girl I'm texting and she usually never forgets to text back so I'm wondering if it's cause I had iMessage off and she tried to send me a message but it didn't deliver?? I've turned it back on since but still don't see a message :/
You will only get the message, if you still had iMessage enabled on another device, so your cell/e-mail was still registered with iMessage. Then it will sync the message from this other iMessage enabled device.
Otherwise she wouldn't have been able to send you an iMessage, only a SMS or e-mail.