If you are a nonresident alien you should have filed Form 1040-NR instead of Form 1040. If you incorrectly filed Form 1040 and you should have filed Form 1040-NR instead, you will have to file an amended return, Form 1040-X, and attach your Form 1040-NR tax return. Follow the instructions under "Resident and nonresident aliens" on page 2 of the IRS Instructions for Form 1040-X.
TurboTax does not support Form 1040-NR. TurboTax has a partnership with Sprintax to prepare a Form 1040-NR federal tax return and corresponding state tax return for certain categories of nonresident aliens - international students, scholars, and non-resident foreign professionals. Click this link for the details of who can use Sprintax, and to get started. If you do not meet the requirements to use Sprintax, you will have to find another way to prepare your Form 1040-NR tax return.