My work sent me last years W-2 for 2018 instead of the 2019 W-2 by mistake

[xmasbaby0]

Then contact the employer and have them send the correct W-2.    You cannot prepare a 2019 tax return with a 2018 W-2.

[DoninGA]

Did you already e-file your tax return?  If so, then wait for the IRS to reject the tax return and then you can correct the mistake and re-file.

If you have not e-filed, then contact your employer and get the correct 2019 W-2