https://www.gov.uk/get-a-child-passport/replace-a-damaged-child-passport
Get a passport for your child or baby - renewals and first child passports, application form, supporting paperwork, eligibility, costs
getpassportchildreplacedamaged
https://www.gov.uk/renew-adult-passport/replace
How to apply, how long it takes, how much it costs, track your application, unexpired visas, replacing a damaged passport.
renewreplaceadultpassportlost