You can search throughout the entire universe
for someone who is more deserving of your love and affection than you
are yourself, and that person is not to be found anywhere. You
yourself, as much as anybody in the entire universe deserve your love
If you are depressed, or know someone who is, you obviously know what it is. I have had my blue periods but I am lucky that I was never in a deep depression myself. I used to have a girlfriend whom I loved, and still do, who was depressed around 300 days in a year. This had been going on for years. She was clinically depressed, taking medication to be able to function and difficult to live with, for herself and for me too.
This experience made me interested in helping depressed people. I have studied massage and I hope to be able to work with depressed people to study the effect of massage on them. I haven't realized this project yet but I still have hope to do so. Buddhism is also interested in depression, as meditation has some interesting effects on the brain. Some of them, beneficial in fighting depression.
Life looks gray when we are depressed. It is scientifically proven that depression has physical impact on out bodies. Thus people really see in gray undertones.
Don't get me wrong, medication is necessary to cope with heavy depression as it is often a life-saver. Medication is not enough though as the root cause of depression needs to be addressed.
An analogy would be that it is hard to drive with a flat tire (the depression) if you do not fix or change the tire and continue driving on it, you might wreck your car. If you drive on a dirty road littered with glass shards, nails and other dangerous debris (the root cause of your depression), you might repair your tires 5 times, if the cause of the flat tire is not addressed, you'll keep getting them.
Religion is not a cure for depression as is shown in some studies ( Maselko 2008) although many depressed people take refuge in religion. The support of the community helps to cope with the affliction but when the religion is one that sees the follower as a sinner, making the person feel guilty, cases of depression increase.
The first Noble Truth states that life is suffering. Depressed people are a living, blazing example of this. As I say on that page, there is a cause to that suffering and there is a way to stop it. The Buddha wrote a treatise on depression, 2500 years ago.
The first thing to do is to get medical help, be diagnosed and stabilize your depression. Once this is manageable, it is time to work on it.
Some areas where Buddhism can help you:
I think that the first step is to get order in your life. Get some physical exercise, even if it is a 20 minute brisk walk in the evening as physical activity produce serotonine, a key brain chemical to avoid depression.
You can then start meditation. Meditation after physical exercise is always both easier and better as your body is already calm. There are many guides on meditation out there but I recommend my all-time favorite book:The Best Guide to Meditation. It has many forms of meditation in it, many different techniques, from Christian meditation to Buddhist meditation. I'm sure one will fit your needs.
Do not seek a teacher yet unless you really feel like you need support. Start by yourself, see how things go and once you feel more confident in yourself, if you feel the need, join a group or a Zen center.
BE CAREFUL: when we are depressed we are very vulnerable and some cult leaders take advantage of this. Always be critical, take someone with you who's judgement you trust to the meetings or teaching sessions to get their opinion.