Options are :
1) get an income transcript
2) report him and use a substitute W-2 form https://www.irs.gov/taxtopics/tc154
3) get one from SS if he ever filed one
If you just need the information from your W-2, but not an actual copy, you can get a Wage and Income Transcript from the IRS for free. This will contain the information from all the W-2s that were sent to the IRS by your employers. However, it does not include the state and local information (boxes 15 - 20). Go to the following link to get a transcript. You want a Wage and Income Transcript, not a Tax Return Transcript.
https://www.irs.gov/individuals/get-transcript
You have to get another copy from the employer or from Social Security
How to get a W2 copy from SSA
https://faq.ssa.gov/en-us/Topic/article/KA-02501
