being one of the lonely people

It's almost a year now, that I have been completely alone. Not that I haven't seen someone since then, or that I don't have people around anymore, but some sort of mental loneliness. I never had many friends, but some really good friendships that lasted long. But now I feel that they have all gone. I spent a year sitting on my desk at home, studying and that's it. If I write one of my former best friends it only gets into a short conversation and than there is silence for a few weeks to even some months. It is really hard for me to socialise, as I am hardly introverted and don't tend to speak much. I just feel so alone, there is not much joy in my life anymore, no one who I could comfortably share everything that goes through my mind. No one who could hold my hand or could ever love me, as there never was someone before. My life is a rollercoaster ride, I wake up, somehow happy and hopeful for the day. But all I get is work and stress. My feelings are rushing up to purest happiness and down to depression in a few hours. I feel exhausted, overworked and somehow tired of my life. Looking back to when I was a kid, I had dreams and imagined to contribute something good to humanity and find happiness. But as I see it now, nothing of that has come true. I'm living from day to day, time is rushing, there's no moment I can keep, the good times seem to be over. I wish that some things in my life would change and that there would be someone to end my loneliness but I don't even know who to start that.