Yes. I'v done it (actually I kind of just FAKED it)...but it wasnt very well received so now im "back at the drawing board" so to speak.
Key word there is "faked." You may be an introvert or an extrovert naturally, but here it seems you mean you faked social confidence and couldn't sustain it for long, so you gave up (I've done the same).
Of course you can. It depends on how you act and feel. My comfort zone implies hiding away or being in very small, controlled groups, but if I'm in larger groups and I'm feeling confident (through people laughing at my jokes, etc), I become an extrovert. I also become an extrovert if I'm drunk, but obviously that's not what I'm looking for.
Obviously, though, it's also a matter of choice. You might seem more comfortable being introverted, and rationally prefer it (instead of hiding your extroverted side behind all the crap your mind says).
No. It's the way you are wired to process interactions with others, not the degree of social confidence or security you have. You can be a confident introvert/extrovert or an insecure introvert/extrovert. The two distinctions simply indicate if you are more inward-oriented or outward.
Do you think a person can change from an introvert to an extrovert?
I think people misunderstand what introversion/extroversion are. It's not being shy or outgoing, as some people here have said you can have an outgoing introvert or a shy extrovert.
As far as I understand introversion and extroversion are how your energy dynamics work. A introvert is drained by social situations (not to say they don't enjoy them) and recharge by doing solitary activities. For example after a day surrounded by people at work/school a introvert wants to go home and read a book or watch tv. Whereas an extrovert, after a day of being alone at a desk want to go out and have a drink with their friends.
That being said I don't think you can change from one into the other, I have tried to go along and do the extrovert thing and instead of adapting it just led to me getting exhausted and burning out.
You shouldn't want to change anyway, being a introvert isn't bad. I know accepting it rather than thinking I was strange helped me become more confident