Can I resubmit an unpresented conference paper to the same conference?
Considering the COVID-19 pandemic, most people would consider withdrawing from an in-person conference to be a smart and ethical move.  In this situation, it should be fine to resubmit.  If the conference is peer reviewed, you should draw the conference's attention to the resubmission so they do not waste time re-reviewing a paper.
Do not make a habit of withdrawing papers.