"If IRS intervention still doesn't produce the form, you need and you want to file by the tax deadline, fill out Form 4852.
Form 4852 is a substitute for Form W-2 that taxpayers can complete if:
The IRS doesn't allow Form 4852 to be filed electronically, so you'll need to paper file your tax return by printing out the necessary forms and mailing them to the IRS."
TurboTax article: What To Do If You Haven't Received a W-2
You can file a conventional paper return that includes IRS Form 4852 if you haven't been able to get a W-2 from your employer. Returns including Form 4852 can't be e-filed because of IRS regulations.
Follow these instructions to fill one out.
TurboTax FAQ: How do I file a substitute W-2 using Form 4852?