When using the Desktop/CD version of the program, the only place your .tax20nn file exists, is on the computer you prepared the return on, and any backups that you made. TurboTax does not have a copy in any format, of your tax file.
If anything, take the hard drive out of the old computer and install it in the new computer as a secondary hard drive. Then you'll find all your tax files on that secondary hard drive in the [drive letter]:\Users\[loginname]\Documents\TurboTax directory. just copy the contents of that folder to the documents\turbotax directory on your new computer.
If you imported from that PDF, the information imported is extremely limited. All you got was the data under the personal info tab. So if you have rental property on SCH E, none of the prior year's data such as depreciation and carry over losses were imported.
But you'll be able to enter that data manually from the PDF, provided of course you have the "entire" tax return that includes all the worksheets and calculation forms.
If you used desktop software downloaded/installed from a CD to your own computer, then the tax files are stored locally on your own hard drive or any backup device you used like a flash drive. They are not stored online. If you cannot recover them due to a hard drive failure, etc. you can get a free transcript from the IRS or for a fee of $50, an actual copy of the return.
https://www.irs.gov/individuals/get-transcript