I had returned to my home country in 2019 and I have received a W2 for 2020 with federal tax paid. Am I still eligible to file for tax refund?

[LynnN82]

Yes, if you were a U.S. resident, working and receiving a Form W-2 with income tax withheld that will be refunded if you file a return, you should. If the income amount was greater than the threshhold for filing, you should file a return to comply with the law.

A return is required to be filed when an individual's income exceeds:

single . . . . $12,400  

married filing joint or qualifying widower . . . $24,800

head of household . . . $18,500

You might also want to check the Tax Treaty between your country and the US to check on complexities beyond simply filing or not.