I feel like I ruined my life by going to university
How did going to university ruin your life?
I used to study math, but I quit after 1 semester. Now I feel like I can never go back.
You shouldn't feel like you should go to college if you don't like it. There are plenty of other acceptable ways to further your education.
Then I never learned anything cool.
It is unfortunate that school dampened your enthusiasm for learning, but you can still rekindle that spark by learning things on your own or in a different setting with friends. It is never too late to find a way to learn something cool.