Depression often accompanies trauma. Traumatic events often involve loss and sometimes the loss is severe enough to cause depression.

In major depressive disorder people feel depressed. They may find that they no longer enjoy what they used to. Their sleep may be affected, generally sufferers find they wake in the early morning and cannot fall asleep again. Alternatively they may find they are sleeping more than usual. Your appetite might be affected. You may find that you have no appetite and may lose weight. Or you might find you are eating more. Often carbohydrates, not brocolli. You concentration may be poor. People will sometimes say they struggle to read a full sentence without losing concentration. You might also find that you have become very forgetful and you have to write down everything. Your self-worth may drop or you may struggle to make decisions. This can even be in everyday situations such as choosing the right breakfast cereal. Your energy may be very low and you find yourself getting tired far quicker than usual. People sometimes find they become agitated. You struggle to settle down and do something. Sometimes it goes the opposite way and you find yourself struggling to move. Your movements slow down as does your thinking. Another symptom of depression are suicidal thoughts. You may find the thought of suicide coming into your mind repeatedly. We become concerned when these thoughts become definite plans. 

If you have plans to commit suicide, please contact the emergency room. They will refer you to a psychologist or psychiatrist and consider starting with medication. 

Since we agreed to let the road between us
Fall to disuse,
And bricked our gates up, planted trees to screen us,
And turned all time's eroding agents loose,
Silence, and space, and strangers - our neglect
Has not had much effect.

Leaves drift unswept, perhaps; grass creeps unmown;
No other change.
So clear it stands, so little overgrown,
Walking that way tonight would not seem strange,
And still would be allowed. A little longer,
And time would be the stronger,

Drafting a world where no such road will run
From you to me;
To watch that world come up like a cold sun,
Rewarding others, is my liberty.
Not to prevent it is my will's fulfillment.
Willing it, my ailment.

Philip Larkin (1922-1985)

As I have mentioned, it may be suggested that you use medication. You can consult your general practitioner or a psychiatrist. Medication is often helpful, but may not be sufficient. If you see a psychologist for the depression, they will consider whether the trauma you have experienced has contributd to the depression. It’s often difficult to give precise causes for depression. And resolving the depression now does not mean you will never have another episode. Even if you feel better about the trauma you have experienced, it does unfortunately not mean that you will not have another depressive episode. Your body has learnt to respond to stress with depression and that we cannot change. You can learn ways to live to minimise your risk for developing another episode.

One approach to managing depresssion is Behaviour Activation (BA). There are many techniques, but this is a relatively easy treatment with a good response. In BA start by choosing some activity. It should not be too complicated or difficult. For example, if you are struggling to get up in the morning, you can decide you will get up at a particular time, and shower and dress for the day. If you are depressed but you are managing self-hygiene, you could decide you will go for a brief walk, or you will phone a friend, something like that which you have been neglecting. Do the activity. After doing it, evaluate it. Did it make you feel slightly better, slightly worse or the same. If slightly better we try a similar activity. If it made you feel worse or you did not feel much, do it again and check if the result is the same. If the same, try something else. We want to increase activities that make you feel slightly better. During this we also focus on thoughts. When people are depressed they tend to have very negative thoughts which they may ruminate on. When you notice you are having repetitive negative thoughts, one possible technique is to acknowledge they are there and postpone thinking about them until later. When the time comes that you set to think about them, you can for fifteen minutes and then postpone again. You can also look for other techniques in the booklet published by the WHO in the references.