You can use TurboTax to file for tax years 2018 thru 2016 by purchasing, downloading and installing on a personal computer one of the desktop editions for each tax year required from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/
Prior year tax returns can only be printed and mailed, they cannot be e-filed.
If you cannot obtain the W-2 from your employer, then for a fee you can get a complete copy of a W-2 from the Social Security Administration - https://faq.ssa.gov/en-us/Topic/article/KA-02501
You can get a free Wage and Income transcript from the IRS - https://www.irs.gov/individuals/get-transcript
