Can I access the 2018 return submitted by TurboTax Software for my PC? For my C Corp. Thanks!

[xmasbaby0]

No.   If you used TurboTax for Business for a return for a C corps then the return is stored only on your own hard drive--it is not stored online.   When you use desktop software, the tax file is not stored online at all.   It is on your own hard drive or any back up device you used.

https://ttlc.intuit.com/questions/1901659-find-your-tax-data-file-in-mac

https://ttlc.intuit.com/questions/1900721-find-your-tax-data-file-tax-file-in-windows

 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 your tax return.

https://www.irs.gov/individuals/get-transcript

https://www.irs.gov/pub/irs-pdf/f4506.pdf