Are you really being audited--or did you get some other sort of letter from the IRS?
TurboTax does not receive any information from the IRS or your state after your return was filed, so no one at TurboTax knows about a letter you received from the IRS or the state.
(what the letters from the IRS mean)
I GOT A LETTER FROM THE IRS
I AM BEING AUDITED
If you purchased Audit Defense:
TurboTax has a special phone number for help with IRS/state tax letters, which will be easier than going through regular Customer Support. At the page below, click on the blue button that says "Get Help from TurboTax Support". Then it will ask you what tax year is your letter. Then it will ask you what the letter concerns. Then it will show you the phone number during posted business hours.
Assuming that you are referring to a 2019 tax return that has already been filed. You had to purchase the Max Benefits package, which includes Audit Defense, before you filed the 2019 tax return in the File section of the program on Step 1.
If you purchased Max Benefits you would have received an email for how to access Audit Defense. See this TurboTax support FAQ - https://ttlc.intuit.com/community/using-turbotax/help/when-will-i-get-my-audit-defense-membership-in...
If you did not purchase the Max Benefits package you can use the TurboTax Audit Support Center for assistance with an IRS letter or notice you received. The Audit Support Center can provide assistance in understanding the IRS notice or letter and provide you with steps on how to proceed.
Support is open from 5am to 5pm Pacific time, Monday thru Friday
Go to the Audit Support Center website for assistance during business hours - https://support.turbotax.intuit.com/irs-notice/audit-support/