There are 3 ways you can obtain this
1. You can contact that employer to get a copy of it.
2. You can get a W2 transcript from the IRS / https://www.irs.gov/faqs/irs-procedures/copies-transcripts/transcript-or-copy-of-form-w-2
3. You can get a copy of the W2 from your local Social Security office. They will charge you if you get it here.
