Hi. As per me some more details are required to make a complete diagnosis. But on the basis of information provided ,like not able to enjoy anything , these thing persistent for long time, a chronic sadness and getting distressed by small matter ,point to diagnosis of either disthymia or depression depending on your socio- functional decline. This is a condition which need a intervention by psychiatrist who will evaluate the need for medication and prescribe you one if required ,else may only advice on therapy, specially Cognitive Behaviour Therapy. It will help you deal with your situation and help you come out of it