Why do you not have a copy of your tax return? And what tax year are you referring to? We can tell you how to get one.
And please explain more about what you mean by "fix my tax refund."
Do you need to correct a 2018 return that you have already filed and was accepted? i.e., do you need to prepare an amended return? If so, we can tell you how to do that with TurboTax.
Or did you efile, and it was rejected, and you need to correct it so you can resubmit the efile?