Dear Tophera Grace,
I am a retired elementary principal from Wisconsin. Before I was a principal, I had a number of years experience as an elementary and junior high school teacher. Having established the aforementioned, let me first state the obvious, this is a really tough situation to be in and while there may be a solution, it will not be easy, that's for sure. But, you asked for suggestions, so here goes.
I think the best way to proceed from here is to first work on building relationships between you and the students. This is because they have failed so often in the past, that failure itself has become a cohesive force which binds these students together in their refusal to try and their rejection of anything that reminds them of their previous failures. In order for you to succeed to any extent you have to metaphorically speaking, penetrate their group, so in the end they see you as a friend and a mentor, someone they can trust. Your next lessons, at least for a while, should be focused on gaining their respect and trust and getting them involved in activities in class wherein they can succeed. Worry about the curriculum later.
In my opinion, you also need to develop some system of scheduled positive reinforcements that will motivate their efforts as they proceed and progress. There are essentially only five different schedules of positive reinforcement that exist. They are as follows: Continuous, Fixed Ratio, Intermittent Ratio, Fixed Interval and Intermittent Interval. The two I would suggest you use are Fixed Ratio and Intermittent Interval. In fixed ratio reinforcement the goal is to positively reinforce someone, or the class as a whole, after every so many times that a certain behavior or achievement occurs, in aggregate or individually. For example, maybe if 75% of all students can score above at 85% or above on 50% of the classwork for a week, the class gets to do something they enjoy, like watch a movie in class, get 15 more minutes of lunch, get to read car and glamour magazines in class etc. The reward has to be something doable and most importantly, something they truly desire to do.
Intermittent interval works on the same premise as that of a Los Vegas slot machine. You know a reward is forth coming at some time in the future, but you don't know what its going to be ( in a slot machine's case this would be not knowing the amount of money you are going to win) and you don't know when the reward is going to be given. With a slot machine, you just have to keep plugging money in and hope you will turn-up a winner before your money runs out. This is the most powerful schedule of reinforcement of all. This is why so many people get addicted to gambling, its because an intermittent schedule of reinforcement and the overwhelming surprise that occurs when it happens is so behaviorally intoxicating. An example of intermittent interval in a classroom setting might be, you tell the class that you have three progressive goals of learning to work on, any of those that choose to put forth the required effort may win highly desirable rewards, at any given time of the teacher's choosing. Here, be creative with rewarding, and make sure there is a 'wow factor' established to especially the first rewards given out. Make sure everyone sees what the rewarded student got. (Try involve your principal's and colleagues' support in coming up with 'wow rewards' that make your students sit-up and take notice.
Remember it is crucial, first to work on your relationship with the students. Have lunch with them, or have a before school get- together, during these informal times talk to them about their own life outside of school, tell them about your family background and interests. In other words, take some time with them to take off the mask of 'teacher' so they can see you as a person and you can come to understand their personage, as well. The power of showing a sincere and honest interest in them as people first and then as students cannot be be overstated, and especially at the junior high level wherein so many many kids act the way they do because of a lack of confidence and low self-esteem. Knowing what makes them tick will not only assist you in understanding their needs, but will also give you some good ideas as to what may motivate them. Then implement your plan to build on their successes over time.
I hope this helps you in some manner or least gives you some ideas. Take care and good luck!