Although it's been a while, I can relate. I used to be so quiet that people would tell me off for whispering. I would never initiate a social interaction, and would definitely never be the one to ask anyone out (friend or otherwise). I can also relate to the constant state of numbness and the isolation, which can make facing each day seem all too daunting. Life seems to loose all meaning, and you can't possibly imagine it ever getting any better. I could only experience two states of emotion back then. I was either numb to everything (emotions, stimuli, I didn't enjoy anything I used to anymore), or I was overwhelmingly depressive. To be honest, I didn't think I'd ever find a way out of that scenario, and my worst fear was that I would continue to live out my whole life the same way.
This was how I used to feel on a regular basis, but I've since learned to overcome this period of my life. How I did it was I had finally reached a point where I simply didn't want to feel like that way anymore. It was a decision that changed everything. I didn't have much motivational drive to speak of, but somehow I forced myself to find an alternative. A little bit everyday, I would do things that worked to reverse my situation. This included trying things I would normally never try, exposing myself to positive stimuli (even if it didn't work right away, it eventually did), deciding who I wanted to be, then working towards it. A little bit at a time, everyday. The one thought that helped me through it all was the realization that failure was surely better than the endlessly depressive rut I was stuck in.
I don't know whether sharing that helps, but hopefully it does. If you were to ask me if it was worth all the trouble I went through, I would tell you that I'd do it all again if I had to. You could say that I now feel like a whole different person. The memory of those days feels more like a distant ghost of a previous life. The fact that I can say that at all still feels surreal, given that I used to think I could never find a way out of that phase. These days, I still like my alone time, but have learned how to talk to those around me (even if it's still a bit awkward). I've learned to project my voice louder, to talk on the phone (which I hate, but can manage well now), to initiate social interactions (still awkward, but I'm still getting by), and I've learned how to feel happy again, and I can again enjoy the things I had once forgotten how to.
I don't think it was accurate to call what I had shyness, but rather anxieties. Fear that I would be ridiculed or judged, or that something bad would happen, if I were to face my fears. If it interests you, I've posted a link to a video regarding a woman who was able to get help overcoming her anxieties with the help of a professional. Of course, the fear is not socially related, but the theory should work in the same way.
