If you are asking about the status of a 2018 tax return that you filed, the only way to find the status is to talk to someone at the IRS. They have very limited phone support so it is very hard to talk to someone. If your 2018 return was filed in the last few months, the IRS has probably not even opened it yet since they did not process mailed returns for many weeks and are way behind.
If you are asking about accessing a 2018 tax return that was filed using TurboTax online, use this link to find it:
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-access-my-prior-year-return/00/270...