Find yourself a 'Wingman' a mate you can hang out with and preferably one who gets invited to parties all the time or likes to go Clubbing and if you are feeling insecure you can always 'fake it till you make it'
Don't change your personality, just be a better version of yourself, as once you start to mix with girls then you will start to wonder what all the fuss was about.
Also consider joining one of those 18-30's Social Clubs like I did a few years ago.
I was very nervous about going along but when I got there, the women outnumbered the guys and in no time at all I felt like a kid in a Sweet Shop, when my Social Life went from Zero to completely off the scale!
I didn't even have to try or come out with any fancy pick up lines, the girls were literally throwing themselves at me, with more dates than I knew what to do with.
Time after time I kept asking myself, what were these girls doing here, as many of them were so hot, that they shouldn't have any trouble in finding a boyfriend.
And to this day I still can't answer that question and if I wasn't over 30 now, I would still be going there today.
So if I were you, that would certainly be my first port of call and don't be afraid to go on your own if you have to, they really made me feel Welcome right from the off and in no time at all I just felt I was one of the guys.
The Power in a Relationship always goes to the one who cares the least