I am 23 years old with server back problems and not allowed to do a lot of exerices, I weight 237 when I am only 5'5 I know I am overweight and I hate it it bothers me I have tierd all kinds of diet pills and I want to lose the wieght but I want to lose some of it in a quickly time I don't want to have to weight a year to get 40 pounds of I want to be at least 160 again how can I lose weigth fast and healthy I am desperate

Check with your doctor or a physical therapist and find out what exercises you can do at this time that won't aggravate your current back problems. Swimming might be a great option or some walking. Don't worry if you can't do much to start with... just keep going and you will start to see that you can go longer as time goes on. You can even do some exercising sitting down as well... using some free weights for example while watching television. Do you know if your back problems are due to your weight or just compounded by it? As you loose some weight, your back will likely show some improvement.

Once you have a list of what you can do, start working on them on a daily basis. Something every day!

If it helps, record for several days everything you eat so that you can see exactly what and how much you are eating. If you live on your own, check out what's in your kitchen and get rid of anything unhealthy. Make a list and go shopping to restock so that you won't have temptations readily available.
Start reducing your portion sizes and changing out any junk food for healthier choices. Some people can do it all at once, some do better with a gradual change. You will have decide which will work for you. Have some healthy quick snacks always available to curb any munchies... carrots and peanut butter, apples, grapes, a few whole wheat crackers, etc..
The key is to stick with it... even if you slip up, get back on track the very next day.
As you start to see some changes... walking farther for example, you will likely gain more enthusiasim to keep at it.

Don't expect it to be fast... to lose the weight in a healthy manner, it will be gradual... this will also make it more likely that you will be able to maintain the weight loss as well.

Focus more on the healthy changes you are doing than on any numbers on a scale. The weight loss will come as you make the necessary changes in lifestyle.