need advice

Well, it's possible you might find some aptitude in high school physical education that will get you a way in. You are going to have to work very hard, in any case.

Depends on if you're desperate to win and be successful, or just want to have some fun.

Geez, what are you 14? That's not too late for anything. There are 84 year old people who run marathons.
http://www.runnersworld.com/boston-marathon/84-year-old-holocaust-survivor-says-running-saved-her-life

You will likely not win trophies or go pro or any such stuff. And neither will over 99% of those people in your class who started young.

But there is no reason whatsoever why you can't get fit and play sports that you enjoy. Over the summer, spend time walking, or riding a bike if you have one. Unless it's dark or dangerous or you have to carry too much stuff (or it's way too far), run all of your errands on foot or by bike. Volunteer to help your parents this way, by doing things like picking up that one thing that was forgotten for dinner, or a prescription or the dry cleaning or whatever. Exercising can be easier to take if you've got a purpose.

As for sports, see if you can get to a gym or a league or a pickup game if those are happening in your area. If you want to play soccer (called football everywhere but here in the US), then search for leagues or casual groups that play. If you can't find anyone, then buy a ball and practice kicking it. Go for distance and precision. Practice bringing the ball up the field, and practice passing if you get a friend to join you. You can also practice for soccer by running, for speed and distance.

If basketball is more your sport, then find a pickup game or a place with a hoop (maybe your school). Get yourself a ball and practice shooting and dribbling. Bring a friend and practice passing. Again, running is helpful, but you're only looking for short burst of speed and a lot of endurance. It helps to practice turning and changing direction.

If baseball is your passion then a friend is going to be your best bet. With a bat and a ball, pitch to each other and hit, or you can just toss a ball up and hit it to your friend in the outfield looking to catch it. Practice running, turning on the speed for short distances, and changing direction at angles as that is a skill helpful in running bases. Practice sliding if there is a safe place to do so.

If your sport is something else, then adapt this advice accordingly.

Don't know how to do a lot of these things? The Internet is your friend - try YouTube for demo videos. Or ask the coach(es) at your school.

You're acting as if your life is over.

It's not.

You're acting as if you missed your one and only chance, and you might as well sit at home forever like a slug.

You didn't, so don't.

Look at your high school website - see what sports they do have. Many high schools have freshman teams where it is not expected that you are experienced playing the sport. There are also many sports that kids start in high school that are not as popular when kids are younger.

I know that field hockey, volleyball are a couple that in our high school many girls had never played before. Even basketball some girls tried out for the first time and played on the freshman team. I think the idea of the freshman team is for girls and boys to try something out and see if they like it and for the JV and varsity coaches to see if there is any potential.

Track is another sport that has a variaty of sports to try.

As an aside - we went to a jennie finch softball camp for my kids one year - they had many of the current and former professional softball players there - one in particular only started playing softball in high school. If you have talent and athletic ability, try out a sport you are interested and see -

Where will you be if you don't try out one of the sports in 4 years? The worst thing that could happen is you don't make the team - however, in our high school pretty much every freshman that tries out at the least makes the freshman team (unless there is just such a huge number of kids).

I also just noticed you mentioned the Y - then definately look at some sports you are interested in - see if they have them at the Y and when - then join usually they are not that expensive and you will get an introduction to see how much you like it.

Team sports in high school are not the only sports teams out there.

Don't forget your community parks and rec. leagues.

Totally agreeing with Jespah.

I didn't start running until my thirties and I was never a fabulous runner but I enjoyed it greatly. I also finally learned to swim without having to cling to the side of a pool when I was in my later thirties. That can be pure joy.

I started both of those at the Y.