Can i edit my taxes after i already filed?

You can file an amended return.  If your parents COULD claim you, you cannot claim yourself, even if they did not.

Someone made an error, but why do you think it was you?

If you are under 24 and a college student, you may still be a dependent, even if your parents don't claim you.  (I think you are a student since FASFA uses "independent," but the IRS does not.)  If so, see IRS publication 501 and to the support test worksheet.If you are 20 and NOT in school and had earned income of $4300 or more, then you weren't a dependent because your income was too high.  

Whoever made the error can file a form 1040X to make the correction.  

You clearly don't know how to file taxes.  I suggest you hire a CPA and get it done right - next year.  This year, you can file an Amended Return.  Good luck.  If your return is wrong, the IRS will redo it and their fee for redoing your tax return properly will come out of any refund you get.  If you owe, then you will owe more.

You would have to file an amended return Form 1040X, BUT you can't just change your status because you want a check.  It doesn't matter that your parents didn't claim you. What matter is if they COULD claim you.  Read the rules regarding who is and who isn't a dependent in IRS publication 501.  There is also an interactive assistant available on their website to help you determine your status.