How do I research other years to see if I need to do anything
To research other years, request Record of Account transcripts to get all your details here: IRS Get Transcripts.
You can also create or login to your account here: IRS View Your Tax Account.
If the prior years were filed using TurboTax, then see: How do I access a prior year return?
If something is missing and needs to be filed, see: How do I prepare a 2019, 2018, or 2017 tax return? and Do I need to amend?