You can calculate your own earnings, as best you can determine, and enter that in your tax software, indicating that you failed to receive a W-2 from the employer. The IRS will be very generous with you as far as accuracy and withholding.
The law says that these must be sent to employees by January 31st of the following tax year.
I had this situation in my past, years ago, and could not get anyone to deal with the issue. I filed, I got a refund and my return was "accurate".
Whatever you report will show on your Social Security earnings record, as well, unless formally corrected.
