What can I do if two of my employers can’t provide me with my W2?

[HelenC12]

You can enter substitute W-2's to complete your tax return(s) but you won't be able to e-file. See  How do I file a substitute W-2 using Form 4852?

[Mike9241]

you need to find out if those employers were treating you as an employee (you can report not getting w-2 to IRS)  or an independemt contractor (should have gotten 1099-NEC if paid over $600.

see IRS tax topic 154

https://www.irs.gov/taxtopics/tc154  

[Saugustine]

You can estimate your wages, Federal taxes withheld, SS paid, Medicare paid and State taxes paid using your last pay stub given to you by the employers.  If they were not withholding taxes from you, especially SS and Medicare taxes, and you are sure that you are not an independent contractor (self employed individual) then you should report them to the IRS.

 As for filing your current your return, estimate your income and deductions for the year as following:

1. Payments and deductions to date per your last pay stub +

2. Number of paychecks remaining form the last pay stub you can retrieve X Income and deductions per pay period .

Add these amounts and you come up with all the numbers you need to file a return. 
If you have the employer ID,  Gross wages, Federal Income tax withheld, SS Wages, SS tax withheld,  Medicare Wages, Medicare tax withheld,  State Wages,  State income tax withheld, then you can file an accurate return without a W-2