NEED IMESSAGE HELP

I turned off IMessage for a few days because I ran out of data. I will turn it back on in a couple days. My question is, will I get all the iMessages people sent me when I turn it back on or they gone forever? I was texting someone who ONLY had iMessage (and therefore can only send me iMessage) So I'm hoping I'll get that later. Also, there's another person who I think isn't getting my messages because they're sending as SMS. please help!!