@ssides0809 , you have ( without extension ) till June 15th to file ( but by May 17th. if you owe). So perhaps you can email your employer have them fax or whatever way to send you a W-2.
Also if you were working from SK during 2020, then your earnings are considered local -- your employer should be aware of this -- it is not US sourced, it is Korea sourced. May want to dis cuss with your employer's HR
Is there more I can do for you ?