I don't have my employer's EIN... I don't have any contact with them anymore either

[Mike9241]

why do you think you need their ein?   I you were an employee you got a w-2 and the EIN was on that. if you lost your W-2 you have several options. You should not prepare your return from paystubs

1) use IRS transcript website to get a transcript (after you register if you haven't done so already 

https://www.irs.gov/individuals/get-transcript 

2) pay a fee and get a complete copy from the Social Security

https://faq.ssa.gov/en-us/Topic/article/KA-02501