In 27 Days by Alison Gervais

16-year-old Hadley is the only person who can save Archer Morales, a boy she barely knows---but to do so she make a deal with Death and go back 27 days in time to stop Archer from committing suicide. From award-winning Wattpad author Alison Gervais comes In 27 Days, a story of redemption, first love, and the strength it takes to change the future.