I didn't read the thread, so what I say may all be a repeat.
Loke, I've been there, I've done that. I too had far too low of self-confidence (search for some of my shy threads if you don't believe me). Thinking that I was unattractive when I wasn't (you aren't either). You can mostly overcome it. It will be a long, slow process.
1) You are the only person who is rejecting you. No one else is. If you have few friends, no girlfriends, etc, it is due solely to you choosing NOT to have them.
2) You have to realize that the only possible way to fail is to do nothing. If you never ask a girl out, you'll never go out, and thus you failed. You just rejected yourself out of the dating pool. Thus, no matter what happens if you ask a girl on a date you did better than if you didn't ask one out. A girl saying "no" is less of a failure than never asking her in the first place.
3) Find something that you feel you are good at. Become the best you can at that. Let yourself be proud of it. Whatever it is, it doesn't matter. You can be the best in school, best employee, best soccer player, best poet, etc. Whatever you like to do. Do it well. Now you have something to feel good about, something to talk to women about, something to do with a woman, something to help your struggling confidence, etc.
4) Force yourself into social situations. I don't care how painful it is, just go. Don't sit at home alone. A really, really great suggestion is to take group dance lessons (salsa, swing, ballroom, country, etc). I've seen dozens of people escape the low-confidence shell from dance (me included). Suddenly you'll have tens of attractive women wanting to touch your body and you don't have to say a word and you don't have to worry about asking them out or worry about being rejected. The confidence with women will slowly grow.
5) Do something about your looks. No, you aren't at all bad looking. Pretty decent if I say so myself. But, you don't like them. So change them. Buy a few dumbbells and lift for a few months. Or start running. Watch your body become stronger. Will women like you more? Maybe, maybe not. But if you like the new muscles, you might start to like yourself more.
6) Don't try to get a girl right away. You have to fix #1, #3, #4, and #5 first.