For what year?
Ideally you should go back to who did it and they should amend it for free if it was their error.
For 2018 you could use the online version by first recreating the original return exactly as filed. Then pay the fees and say to mail it and print it out so it think you filed it. Then when it matches every line you can amend. How to amend an Online return https://ttlc.intuit.com/replies/7276596
For2018 or prior years you can buy the Desktop CD/Download program here, https://turbotax.intuit.com/personal-taxes/cd-download/
You can recreate the original return using the Forms Mode. Then say to mail it. How to amend, https://ttlc.intuit.com/questions/4667229-how-do-i-amend-my-2018-return-in-the-turbotax-cd-download-software
So in order to amend the taxes I would have to recreate and pay the fees as if I was doing a new return?
If I purchase the software would I just need to recreate the filed return and make the changes to submit?
I'll be adding deductions and expenses that will reduce the total taxes that I paid.
If you did not use TurboTax to prepare your return, it is possible to amend the return using TurboTax but it will really be a pain. It would be better to use the software or service used to file originally. If a paid preparer made a mistake on your tax return, that tax preparer should do the amended return for you at no charge.
In order to use TurboTax to amend your 2017 and 2018 returns, you need to purchase the desktop software for 2017 and 2018 and re-create the return EXACTLY as it appeared when it was filed with the IRS/states. Every line has to be the same. Then you have to "trick" the software into thinking you filed by saying you will mail the return. (but do not mail it) AFTER that, you use the software to prepare a Form 1040X, which has to be printed, signed and mailed to the IRS. It takes the IRS about 3-4 months to process an amended return.