1: Think about something you have done well recently - all of us have projects or activities we have undertaken that we have actually excelled in. Anything you have done whether it's helping someone else achieve something or that you have just tidied up the house. If you remember the good things it will help you feel good about you inside.
2: Do something you have on your "to do" list - if you go off and undertake an activity it will keep your mind off other things that are pressing but also give you a sense of achievement that you have achieved a goal. It can be small like walking the dog, going shopping or cleaning the car or energetic like going to the gym.
3: Do something you really like - again it doesn't matter what it is but if you get a buzz out of something you'll feel good about it. Even if it's reading a book, having a cup of coffee or meeting a friend.
4: RELAX! - Most of us have tons of things we want to achieve and put a lot of them to one side for another day. No problem. So long as every day isn't like that why not just put aside some time today to just relax and enjoy your own company. If you have children to look after why not let a relative look after them today so you can have time to just chill out.
5: Volunteer and help others. If you have time on your hands why not help others in groups. There are plenty of charities and voluntary groups that are looking for people like you to help others. It can be easy tasks like shopping for elderly people or serving tea and coffees at a church. You'll also likely meet new people.
Above all life is for living and it's a shame if you are down and don't want to do anything. Take one step and one day at a time. Find projects to immerse yourself into and small changes one piece at a time all add up in the longer term to make life a great place to be.
If you have close friends you can talk to then they can probably help you as well.