Cut yourself from the wrong things for a while and only allow fresh and positive thoughts to come in.
Whenever I feel low, I always buy stationery (coloured pens, writing pads etc.) or books as these are my best companions and defocuses me from the worries or the bad things happening.
I also engage myself in doing things which I love the best, like reading what I like, writing what I feel or even drawing with colour pastels (I am no artist). Actually I involve myself deeply in my favourite activities, it helps me resume self-esteem, self-respect, self-appreciation and self-satisfaction which I need the most to remain positive and recover from whatsoever depression.