Trying to get 2016, I have 2 emails on our taxes, 2018 and 2017 are on one email and 2016-2010 are on another email.

I trust you are saying you have 2 User IDs (2 accounts).   A User ID can be an email address, but it doesn't have to be.

How you access the 2016 return depends on what you have done for 2018.  Have you already filed the 2018 return?  If so, was it in a paid edition (PLUS or higher), or was your 2018 return in Free Edition?

Yes, and have recieved the return. I need it because we are getting a new house

I'll assume you are the same person as the threadowner, although your screen name is now quite different.

You didn't answer everything above.   Was your 2018 return prepared in a paid edition (PLUS or higher), or was it prepared in Free Edition?

Also be aware there's a free option if a tax return transcript would suit your purpose.  Many loan companies will take a transcript if you ask them.  You may be able to immediately download a 2016 return transcript at the IRS website at the link below.  If you don't qualify to open a free IRS account there, you can order one to come by postal mail, which normally takes 5-10 calendar days.   
<a rel="nofollow" target="_blank" href="http://www.irs.gov/Individuals/Get-Transcript">http://www.irs.gov/Individuals/Get-Transcript</a>

Otherwise, we can tell you what to do when you answer my question above.

Yes, i did. Plus

OK.  Since you paid for PLUS in one account, but the locked return is in the other account, you can phone TurboTax Support and just ask them to unlock the other account.    That will keep you from having to pay twice to unlock it.

Support hours 5AM-5PM Pacific (8AM-8PM Eastern) Monday-Friday.

FAQ:  What is the TurboTax phone number?
<a rel="nofollow" target="_blank" href="https://ttlc.intuit.com/questions/1899263">https://ttlc.intuit.com/questions/1899263</a>

Or you can use the contact form at the link that Critter left in Part 2 of her answer below.

Since  you didn't file or pay for a 2018 program under the same account that you used for the 2016 return ... then you have 2 options.

1) Pay for the 2018 program to unlock the prior year returns 

You have to start a 2018 return using the Free edition from this website - https://turbotax.intuit.com/personal-taxes/online/   

(If you already have the Deluxe version or better chosen then you can skip the upgrade and go straight to the payment instructions)

You must enter some basic personal information in the Personal Info section of the program.  Click Upgrade, located near the top of your screen.  In the pop-up window, scroll down to the bottom, select TurboTax Plus, and click the Upgrade Now button.  If you want to include a state program with your order click on State Taxes and complete some of the state section.

To pay for the upgrade so you can access your prior year tax returns, assuming that you signed onto your 2018 account with the exact same user ID you used for the prior returns -

To pay the TurboTax online account fees by credit card, without completing the 2018 return at this time, click on Tools at the left side of the online program screen.  Then click on Print Center.  Then click on Print, save or preview this year's return.  On the next page, to pay by credit card, click Continue.  On the next screen it will ask if you want Audit Defense, if you do not want this option just click on the Continue button.  The next screen will ask for all your credit card information so you can pay for the account.

                                                                             

2) Contact TT support and have them unlock the return since you used another account for 2016:

Use the following TurboTax website to contact TurboTax customer service/support

There will be some personal information gathered so a case can be created for you. A phone number will then be provided, specific to your case, to speak directly with a TurboTax agent.

https://support.turbotax.intuit.com/contact/

Note:  The Call option will not be available when TurboTax Support is closed.