If you used Turbotax online, log into your account and look for your prior returns. I don't know how long Turbotax Online keeps them.
If you used Turbotax on your own computer, only you have copies of your tax returns.
You can also get a transcript (electronic record) of your tax returns from the IRS.
https://www.irs.gov/individuals/get-transcript
You don't file more than one return if you have more than one source of income, you file one return that lists all your income, deductions, dependents and credits. If you don't receive a refund, or if the refund is less than you expect, you need to talk to the IRS. Usually they send letters if they change something, but if you moved and did not use forwarding at the post office, you might have missed the letters. The electronic transcript will show you what the IRS has on file for you, including what you filed and any adjustments.
