Very few girls like to be alone. As soon as we near puberty, we began thinking about all those romantic movies we've seen, and fairy tales we've read, and we dream about getting a boyfriend. Having a boyfriend will prove to people that we are worthy - that we are cute or sexy or friendly enough to have a guy like us. Having a boyfriend means there's someone to flirt with on the phone, someone to go to movies with, someone to go to dances with. It can be exceptionally rough if all your friends have boyfriends, and you are still ... single.
The key here is that you CANNOT look at this as "I need a boyfriend to be complete!" I know it's frustrating, and I know you want to be like everyone else. However, after talking with thousands of young women, I can tell you it simply doesn't work if your mindset is "I need a boyfriend". That puts you in the mindset of being desperate for a guy. Guys can sense that desperation. They stay away. This makes you more desperate. This makes them stay even further away. You dig your own hole.
Remember, there are pretty much the same number of guys as girls in the world. So the guy that is good for you IS out there. The key is to ensure you are in "a good state" to attract him - and that you are in a location where he can even meet you to be attracted to you.
So, step 1. You need to be a person that the guy would want to be with. Guys don't fall for tricks and schemes. They get pretty cynical pretty quickly about "psycho-girls" who lie and play games in order to trap them. They want someone who they can trust. Look at all the stories about guys being used for their money, being cheated on, and being played for a fool. Guys can be insecure, and they want to know the girl they are with can really be trusted.
So you need to AUTHENTICALLY, honestly, be someone that a guy would enjoy being with. This doesn't mean being a fake! But as many self improvement books will tell you, it is about how you feel about yourself. Let's say you spend all day being grumpy, complaining about your life, pointing out all your flaws and yelling at people. Very few guys will want to be around you. Now let's say you work on changing your outlook, on being accepting of those around you. Say you learn patience and tolerance. You learn to see the bright side of things. So now you look exactly the same way - and you are the same person - but now you are a smiling, happy person who genuinely is content with life. That is the sort of girl that MANY guys want to be with! There are thousands of tips on this site on how to go about becoming more happy. You have to naturally, innately be a happy person to attract the most guys. It's something every one of us can work on.
Next, a lot is said in the media about looks. I understand that some guys focus solely on big boobs and a perfect body. To be honest, the girls who end up with those guys usually end up miserable - because the guy is always willing to "trade up" and abandon that girl, when he finds someone who looks better. It's not worth it to catch a guy who is solely interested in looks. Looks fade and someone else is always going to look better. You want a guy who likes YOU, even if in 10 years you are a little more wrinkly and weathered.
That being said, people do make first impressions when they meet. You want that first impression to be a pleasant one. You want it to accurately reflect the kind of person you are. So, for example, if you didn't take a bath in 2 weeks and were super-stinky, you might be the perfect match for a guy - but he might wrinkle his nose when he smelled you and not be willing to move closer to find out. There are many tips on this site about presenting yourself well - brush your teeth, use mouthwash, smell clean but not overwhelming of perfume or aroma. Wear clothes that highlight your good features. EVERY one of us has good features - our eyes, our smile, our hair. Whatever yours are, read up on ways to highlight them. This isn't about piling on the make-up or flashing the boobs. It's about showing the guy that you respect yourself and care about yourself. It is the surest way to intrigue him, for him to wonder if he should learn more about you. Few guys will want to get involved with a girl who doesn't respect herself, who puts herself down all the time. As the saying goes, you have to love yourself before others can truly love you.
Finally, you have to be somewhere that guys ARE. If you go to an all girls school, and that's all you do every day, the chance of meeting a guy is slim. Think of interests that you have. If you love skiing, join the local ski club. If you love hiking, go out on community hikes. The more that you put yourself into social situations that have guys - and that involve your favorite hobbies - the more likely you'll find a guy who will adore you. I know it's hard. We all are shy. The only way to get less shy is to PRACTICE. Make it a weekly task, to practice at your shyness. We have tons of tips on this site to help out.