"should have been withheld" does not change your situation for right now. You will need to enter the W-2 as it appears---and if you owe---then, sorry-- but you owe. Complete a new W-4 for the employer and watch your paychecks and pay stubs carefully to see if they are withholding tax gong forward.
W-4
https://turbotax.intuit.com/tax-tools/calculators/w4/
https://www.irs.gov/individuals/tax-withholding-estimator
https://www.irs.gov/pub/irs-pdf/fw4.pdf
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
