Moving on and looking for work.

I had a car accident last year and decided to leave my job earlier this year to concentrate on finishing uni. Now that I'm finished (and doing much better), I'm looking at getting back into the workforce - only problem is, most jobs want you to have your current or immediate past supervisor as a referee. I'd had lots of time off in my previous job, which my boss wasn't too happy about, and I've been "thrown under the bus" before.

Question is: how can I approach the issue with prospective employers? Can' I just say I'm not in contact anymore and provide a colleague (which is technically true, since boss no longer works there)? Also, do I have to bring up my past history? I've been told that they're not supposed to ask, but I had it backfire on me really badly and now I don't know what to do?