Does anyone know if i am able to file back taxes for last year with this current year? As in can i add the refund to my current refund? Or file a whole new return?

i have a current refund pending due to me trying to find out answers if i am able to add my return from last year as i wasnt able to file due to issues. so i have already finished filing for this tax season, am i able to add last years or do i need to file a whole new return?