Hi I'm 15 and I weigh 121 pounds
I play a lot of sports
I want to lose weight around my legs and stomach
But its so hard. I do some crunches every night but nothing works.

What type of things do you eat?
Cut out any junk food, prepackaged processed foods and bad oils as much as possible.
It takes at least 102 days to get rid of bad oils
Such as Crisco/Wesson.
It takes 240 days to get rid of Hostess type snacks.
If you keep eating these type things you are only going on a vicious circle with weight loss because you put the stuff you just worked off right back.

Even many foods that claim they are healthy are not healthy. Like read the ingredients on the back of things like nutrition bars.
A good rule of thumb is if the list is long and you don't know most of the words it is unhealthy.
If it says fortified with or added calcium, vitamins, etc... most often they are altered synthetic and again they are packing on the weight.
Most sports drinks are not even good even though they contain things like ginseng and taurine. They have high sugar content for one.

Also switch to sea salt. Throw your table salt away.

Your weight really doesn't sound that bad though
How tall are you?

How tall are you?

I'm 5''2

It sounds like you're exercising a lot. Just make sure you're not consuming even more calories than you're burning because that's what makes you fat (I'm not saying that you are though. Your weight actually sounds pretty good for your age and height.) You could also try eating more fruits and vegetables and fill up on them.

You sound about right to me. Remember, muscle weighs more than fat. So, if you are muscular you are going to weight more.