Stokes and fast bowler Gus Atkinson have both been left out of England's squad after breaching the team's midnight curfew in London earlier this week.
The pair were reportedly present when a member of England's security staff was struck during an altercation involving Saracens rugby player Totoa Auvaa.
With Stokes unavailable, England have turned to former captain Root to lead the side. Despite serving as vice-captain, Harry Brook was overlooked for the role.
Root previously captained England in a record 64 Test matches between 2017 and 2022 before stepping down. The 35-year-old remains England's highest run-scorer in Test cricket and now returns to the leadership role for the first time since handing over the captaincy to Stokes.
England have also made changes to the squad, recalling fast bowler Jofra Archer and batter Jordan Cox ahead of the second Test.
The hosts take a 1-0 lead into the match at The Oval after securing a 115-run victory over New Zealand in the opening Test at Lord's.
