Hey strawberries!
Sounds like a bit of a predicament!
Do you know if any colleagues from your old job still work there? Could they potentially be a referee? Also I see you said you worked in fast food - even if the old managers aren't there, if you get in contact, hopefully the new managers might be able to help out
Otherwise, I'd recommend having a chat to some staff at the uni - I think there are careers advisors and all that? They might have some suggestions.
You could also potentially approach your unit coordinators, even if you don't know them

Even if they can't help, they might be able to point you in the right direction.
I'd also recommend contacting your school - I don't think your teachers actually hated you, and potentially even the head of senior school or someone in one of the more senior positions might be willing to help out

Worth a shot getting in contact. It's certainly the case at my high school that they're willing to help their alumni out, so hopefully it might be the same at yours.
Worst comes to worst, you can always put friends down - they can be great as character references, and it's better than nothing. Maybe also consider seeing if you can do something volunteer-wise to start getting to know some people that could also act as referees in the future?
There are a number of jobs that don't require you to give referees or won't contact them - these tend to be the ones where hiring is done in person (i.e. not online) where you might just hand in a resume or go in and chat to the manager - sometimes these jobs might be a bit more "dodgy" than other ones, they might be cash in hand, but it's better than nothing.
In response to your second question - play up your experience in fast food. Make sure you put it in there, describe what you did, how it helped you with teamwork skills, etc.

Even if you feel like you didn't learn anything/develop any skills from it, I can guarantee you that you probably did - working under pressure, working in a team environment, and all that.
If you ever did volunteer stuff through high school, put that in there.
Hope this helped