any refund for 2018 is lost. if you owe the IRS can come after you forever. Turbotax no longer supports 2018 return preparation. Turbotax has closed online preparation and e-filing for all years other than 2022 so if you use Turbotax you need their desktop app - Windows or MAC - no mobile phones.
Turbotax prior year apps (other sites may offer online preparation)
https://turbotax.intuit.com/personal-taxes/past-years-products
Turbotax system requirements Windows
https://ttlc.intuit.com/turbotax-support/en-us/help-article/product-system-requirements/minimum-syst...
you can get copies of w-2's from the Social Security Adm but there is a fee
https://faq.ssa.gov/en-us/Topic/article/KA-02501
the IRS has transcripts for free but no state info if you have a state income tax (only the SSA can provide a full copy of the w-2 if you can't get them from the employer)
https://www.irs.gov/individuals/get-transcript
if you had income from sources other than wages you can get those transcripts from the IRS as well
