First see if you can apologize to the catering agencies and get back in good graces with them. You did not give us any details why they dropped you. Speak to a manager there and see if it is possible for them to take your account back.
Failing that try to find other catering agencies in your area.
If you cannot find work by catering agencies try changing your business to one that drives trucks around. This is a company in my area that does well with Korean Tacos http://www.seoultacostl.com/
You might try to find areas you can get permission to park your truck at and cater to the crowds there. I would suggest startups and startup events, and try things like Korean Tacos where you mix one food item with another. A lot of people who work at startups like Asian food.
Consider doing a Kickstarter so you can raise money to do your own food catering agency to serve your business and other catering companies. Maybe build on your web site so it can be marketed better. Put in a program where a startup can request that you cater their events.
Make sure you create accounts for your catering service on as many social networking sites as possible to help promote it. Find web sites on food reviews on businesses in your area and email them to do a review on your business. Advertise in the local yellow pages as well.
I hope this advice helps,