The American Opportunity Credit (formerly the Hope
Credit) provides up to $2,500 for each eligible student per year. It
can be claimed for the first four years of higher education.
If you had claimed any amount of this credit in previous years, you'll see how much at the bottom of Form 8863, Page 2.
Note: you would need to manually check every prior year's return for Form 8863
If you used a TurboTax Online account to file a prior or current year return, you can download the return from yourTax Timeline.
Yes, by filing an amended tax return.
How to amend https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed
There's a new urban myth among college students that says they can get a $1000 from the government just for filing a tax form. For most of them, they simply aren't eligible. A full time unmarried student, under age 24, even if you don't qualify as a dependent, is only eligible for the refundable portion of the American Opportunity Credit if he supports himself by working. You cannot be supporting yourself on parental support, 529 plans or student loans & grants. You usually must have actually paid tuition, not had it paid by scholarships & grants. It is usually best if the parent claims that credit.
You cannot claim a credit if you are, or can be, claimed as a dependent by someone else.
A lot of people are just not eligible. See https://www.irs.gov/Individuals/AOTC