State refund for paying taxes to state I don't reside in
I already filed my 2021 taxes. I live and work in Nevada after moving from IL in 2020. My employer is in IL. They withheld IL taxes for the entire year and a portion of this year before realizing they should not be withholding anything. What can I do to get a refund for 2021 for paying all those taxes to IL? Separate question but related, but since taxes have been withheld for the first 3.5 months of this year, is there a way to have this refunded as well?