Your accountant should have given you copies of your tax returns.
If the accountant used Turbotax for professionals, there is nothing you can do to access the account without asking the accountant for the information.
If the accountant used personal turbotax, they were violating the license agreement and IRS regulations, since personal turbotax does not include a place to put the accountants "paid preparer ID number" and they are not allowed to file for you without that number. You might be able to take over the account by contacting customer support but it will take several days and you will need to fax in proof of your identity.
You can get your IRS transcript for free, that is a computer summary of your tax return. https://www.irs.gov/Individuals/Get-Transcript