Did you know that there are a lot of things your previous bosses can do for you in your quest to find a job? They might have a job lead for you, they can definitely offer insight you can use to be a better job seeker, and they are excellent references. If I were looking for a job, I would call all the bosses I've ever had. They know me better than anyone else, and they remember things about me and my work. And, they probably have a network at a higher level than I do-they know the people I need to be talking to about getting hired. Even if they can't hand you a job, they may be able to hand you a lead. They just might know exactly who you should call.
Even if they don't have a lead for you at that moment, they're still a good call to make. Why? Because in most cases, because that person knows you so well from working with you, they can boost your morale or help you refine your pitch for the job search. Ask them what they liked about working with you, or get brave and ask what they didn't like about you, so you can be better employee going forward.