If you used the desktop CD/Download editions installed on your computer, the only copy of your tax data file and any PDF's will be on the computer where the return was created. TurboTax does not store online any returns completed using the desktop editions.
Go to this IRS website for free federal tax return transcripts - https://www.irs.gov/individuals/get-transcript
For a fee of $50 you can get a complete federal tax return from the IRS by completing Form 4506 - http://www.irs.gov/pub/irs-pdf/f4506.pdf
If you used the Desktop CD/Download program you need the files ending in .tax2018, .tax2019 etc. to open in the program. They are only saved and stored on that computer and any backups you made. And you should have been saving each year as a PDF file when you were done so you have a copy and don't need the program installed to open it.
Why did your computer crash? Sometimes the hard drive is still ok so you can take it out and put it in an external usb enclosure and access it from your new computer.
If you can find the .tax files somewhere......After you get the program installed the first thing to do before you open your tax return is to update the program and install any state programs you had. Then open your file. So you first might need to start a fake return to be able to download the state program (go to File-New Tax Return).
Then go to FILE -Open and find your return.