Background:
I've hung out with this person maybe around 5 times in the last 6 months. It is a casual friendship. It's slowly building. This person does not have Facebook. Let's call them NFU - Non Facebook User. NFU and I only have each others phone numbers. We spoke fairly casually on Monday about maybe hanging out yesterday (Wednesday). I told NFU that I'd text back and confirm on Tuesday evening:

Said and done
No response
Texted back on Wednesday midday "Are we hanging out tonight?"
No response

So here are the alternatives of what might have happened:

NFU is:

1. Busy and not bothered about getting back to me/blowing me off

2. Decided that they doesn't want to hang out with me anymore/giving me the cold shoulder

3. Has been mugged/dropped their phone/somehow deleted my number