You need your EIN and you need your W-2. You will have to double up on your efforts to get hold of the employer--you have had since January.
W-2's come from your employer, and they have until Jan. 31 to issue it. Some employers allow you to import the W-2 through the software, but for security reasons you still need information from the actual W-2 to import it. You might need to phone, drop in, email and/or snail mail an old employer to make sure they know where to send your W-2.
Other ways to get W-2’s:
Pay Social Security $86 per W-2:
You can get a wage and income transcript from the IRS: It will not show the actual W-2, 1099’s, etc, but will show the income information the IRS received. It will not, however, show your state information. It will only show the federal information.
You don't have an EIN. An EIN is an employer identification number, and you won't have one unless you are a small business that has employees.
In some cases, if you have your employer's EIN, you can download your W-2 information into your tax return. But not all employers participate. There's no guarantee you can download your W-2 even if you knew your employer's EIN. You could find out your employer's EIN by asking another employee what is written on their W-2
Your employer is required to mail you a W-2 by January 31, unless you consent to paperless online delivery. You are responsible for keeping copies of your valuable tax documents for at least 3 years (although 6 years is better).
If you never got a W-2, you can file using a substitute W-2 form and your last paycheck, but it will probably be inaccurate and the IRS will be sending you correction letters. It will be best to get another copy of your W-2 from your employer.
You may be able to request a "wage and income" transcript from the IRS that will have the information from your W-2, although I don't know if 2019 wage and income transcripts are in their system yet.