One way or the other, you have experienced a lot of hurts either directly or indirectly earlier on. And I can't blame if that is how you see the world when you go out. But be reassured that there is an answer for it.
Your fear of going out and getting involved with people in varying degrees, has deprived you of certain happiness and contentment in life. I think that this situation of yours is more on how you see and feel towards the things and people around you- but you know what?...there is no need for these things to take control of your life. You must take charge and be in control of your fears. I suggest that you pray to God and ask Him for help. Only He can drive away your fears and help you regain your confidence.
If you do still have a few close friends or family members around you, invite them over to your place for a dinner for instance. Simply take advantage of the time and refresh the bonding amongst yourselves. Ask about any good news that's been happening. I really think that if you invite people who are 'positive' about themselves and the world around them, they will be able to bring in some positive things into your life as well.
Another aspect that you have to consider is whether you have been watching or reading a lot of those sad stories or news? Even those movies that are depressive and violent in nature should not be part of your everyday routine. If you do watch, read or listen to a lot of negative material, what can you expect yourself to think?...I am pretty sure that you can resort to other things that are more productive in nature.
Also, do give yourself a 'chance'. It is a fact that there are still lots of 'bad' things happening around us- but if you keep on letting these things control you or affect you, you won't accomplish anything. You don't have to think too much about these negative stuff. Go out and visit a park or a museum. Or simply take the day off and shop at the store. Or even visit a good friend whom you are really close with.
There is so much more to life that you can really enjoy. Go out and give yourself a break.