If you need a new ballot:
If it's over a week before an election, you may call the Davis County Clerk's office (801-451-3213) to request a new ballot be mailed to you. If it's within a week of the election you will need to wait until Election Day to vote in-person at one of the voting centers located within the county. You will need to bring proof of identity and proof of current residency with you.
https://www.daviscountyutah.gov/clerk/election/how-wherer-to-vote/how-where-to-vote
If you have your ballot but need a new envelope, you can pick one up at the Davis County Clerk's office, or can visit a voting center on Election Day.