Weight loss is very often a problem if you are not in the right mind set, I have in the past tried to diet and failed.
This time I approached my doctor who put me on antidepressants which allowed me to change my mind set.
Now I'm not suggesting that this would work for others, however if you do have a problem with depression a doctor can help, and if not then they are also good people to speak to about weight loss in general.
I was scarred to go at first as I thought that she would judge me about my weight, I couldn't have been more wrong, she has been amazingly supportive and I've now lost 21lbs in just 6 weeks by doing nothing but changing the way I eat and doing more exercise (which has also helped my moods) I'm not saying that I don't still get down days, of course I do, but they are much more few and in between.
You need to acknowledge that being overweight is an issue that can be overcome, it just takes time, effort and determination.
Good luck, there are many people on here that will support you through your journey, I hope you find the presence of mind to start that journey.