I know moe players whose careers were derailed by bad grades or some other off-court issue than players who flat-out could not play. Don't have yourself being another one of them. Here are the things you need to do now, moving forward, to play in college.

If You Didn't Play Because...
You Had Academic Issues
See your school (academic) counselor regarding your college athletic eligibility. Do what you're told to do to get eligible ASAP.
Take extra classes to be ahead of academic pace, not even with pace.
Get a tutor. Pay money for him/her so you'll take it seriously.
Get a study partner or join a study group and earn your spot in the group by actively STUDYING.
Get some new friends. Associate with academically thriving students.
You Had Behavior or Off-Court Issues
Clear up whatever was going on INTERNALLY - that means your personal issues that led to this situation. Yes, there is something if you are in this space. You don't have to have it haunt you, but you also serve no one by acting as if it was all someone else's fault. And no one will believe you anyway.
Get any legal paperwork clearances necessary.
Find a mentor who you respect enough to have them hold you accountable for your actions.
Gather some written recommendations by upstanding members of your community to alleviate any future concerns.
Conduct yourself as someone who would never do what you did do to have that situation. That person no longer exists. This is all under your power.
Get some new friends. The kind who wouldn't encourage you doing what you have done in the past.
You Had No Game
Play as much as you can now and get game experience.
Work On Your F*ckin Game as much as possible so you don't have the same reason to not play in college. The programs here will help.
Find some active college players and play with them a lot. This will raise your game by default if you keep showing up.

Get some new friends. The kind who can play much better than you. Stay close to the money.