How can I get a driver's license if my parents wont teach me to drive?

Basically you can't unless you have a lot of money to spend or your parents change their minds. Learning to drive well enough to pass the test requires a minimum of 40 hours behind the wheel which would cost several thousand dollars if you hired a car and instructor. If you think you can learn to drive competently for under $1000 with only 10 lessons, think again. 20-40 lessons are what most people need.  

You likely CAN buy a car without a driver's license. Go to your DMV and ask them about it. But you still need a teacher, who can be anybody who has a driver's license. 

You will have to wait until you are 18 years old.  Then you no longer need your parents permission.   And, you no longer are required to do a driving school. 

All you need to do is get your permit.   Please post your state for more help.

If you are still in high school, or recently graduated from high school find out if the school offers driver education.  It is free.

You find another relative or friend who is willing to teach you.  My sister's husband taught me to drive.

What you can do depends on where in the world you are.

In California, you can get a 150cc class motor-scooter, get your learner permit, and ride anywhere daytime/non-freeway.  Ride a scoot for a few years and driving a cage will be trivial.

If you can't afford $500 for driving school, how are you going to afford to purchase, title, insure, and maintain a vehicle?

Plus, you can't just go to the DMV and say "My parents taught me how to drive, can I take the road test?".  Follow your state's guidelines.

Read the permit book and memorize it. The rest is common sense. Aim right - go right. Aim left - go left. 

If your family won't help you learn, you need to take driving lessons. Driving isn't free, it costs a lot of money.

Find a part-time job that is near you so you can walk or a short bus ride. Make some money and register for a driving school.