Sometimes after bereavement, people don't know how to express their deep feelings. This can lead to feeling that they are 'bottling things up' which, in the long run, can increase stress and unhappiness.
Try writing down your feelings before you go to bed, as a way of clearing your mind before you sleep. You could write a letter to the person who has died, telling them how you feel and what you miss about them. Getting your feelings out into the open, however you do it, may help you to deal with your grief.
It may help to talk through your feelings with someone you trust. You could talk to a friend or family member about your memories of the person, what you miss about them, how you are feeling, and what you can do to cope.
If talking to someone close to you is a problem because you are worried you will upset them, or they are finding it difficult to cope themselves, then you can seek professional help.
You could also speak with your GP who can refer you to a counsellor. Talking to a trained professional could help you identify your feelings and work through them.