do not use your paystubs to complete the W-2 info.
if your employer won't provide a copy your options are to
a) get a w-2 transcript from the iRS - no state info or
b) get a copy for $126 from the Social Security Admin. The fee might be waived if you can convince them that the employer never sent you an original w-2 but in that case they may tell you to contact the iRS
https://faq.ssa.gov/en-us/Topic/article/KA-02501
