I have these bouts usually after a long relationship where I wasn't spinning plates ends. I usually coped with this by going on a big adventure out of state or out of country because it A) forced me to keep NC and B) I gotta experience a ton of new things.
The only problem with this is that when I get home, I'd get thrown back into the system and routines of every day life and have a reality check clawing my eyes out. I'd get lackadaisical and unmotivated for months, get bored with the women (cause they suck compared to travelling, adventure type girls), and just go into a stupor that involved too much internet, too much drinking with equally depressed friends and the like.
The only way I ever get out of these is to start hanging out with better, happier people and to start feeling some successes in the regular realm of existence. Get a job I really like, work on music with talented friends, make out with different women and yes, fvck them, too, but set the goal low and don't expect sex as the result of your interactions and you'll be elated by even your marginal successes. Then you can transition into bigger successes like getting laid and advancing your projects further in the days that follow with great confidence cause you already see that you're winning at life.
Little easy goals that make you feel like you're improving your life because of your actions and choices. Eat a little better, use your time to read or plan or practice your passions, exercise more than you do. You'll feel better fast, and you'll be on top of your life again in no time.
If you need some understanding, read some encouraging, mind-expanding literature. I personally like tantric philosophers like Osho, it fits my view of reality, but I've also been encouraged by western authors like Heidegger and some Nietzsche. You could also read modern self-help books for the easy reads, but I find most of the content to be pandering and almost condescending. Basically, the stuff I read affirms for that the world is full of ****, but your inner world is only what you allow in, and how to master the self so that you control exactly what's inside you, what you feel and how you respond to life.