TurboTax W-4 withholding calculator - https://turbotax.intuit.com/tax-tools/calculators/w4/
IRS W-4 withholding estimator - https://apps.irs.gov/app/tax-withholding-estimator
What did you purchase?
The TurboTax online editions for tax year 2019 are not yet available for purchase!
The TurboTax desktop editions for tax year 2019 are available but you would have to purchase, download and install the software on a personal computer, Win or Mac from this website - https://turbotax.intuit.com/personal-taxes/cd-download/
Do you mean W-2 (not W-4)?
The TurboTax (TT) free filing option ends Oct. 15 of the filing year (10-15-19 for tax year 2018). It's too late to file free, or even electronically.
If you want to use TurboTax, you will need to purchase the Desktop Version for each year that you need to file. You can do that at this link:
http://shop.turbotax.intuit.com/personal-taxes/past-years-products.jsp
You can download the Forms and Instructions free from the IRS web site at this link:
http://www.irs.gov/app/picklist/list/priorFormPublication.html
A return with only one W-2 should be simple enough to do by hand. If you are required to file a federal return, you may also have to file a state return, if you live in a state with an income tax (41 out of 50).
If you mean you want a refund of what TurboTax charged you:
This is mainly a user community forum, so nothing account-specific can be handled here. Request for refunds should be directed to TT Support. https://turbotax.intuit.com/support/contact/ use the term “billing issues” in the question box, not "Refund" or it will just give you the IRS phone number to check your refund status. Week days 5 AM - 5 PM Pacific time