A teenage girl died of a suspected asthma attack after running up the stairs at her boyfriend's house.
Ellie Leigh Taylor-Ward, 16, fell unconscious and was taken to hospital where doctors fought in vain to save her life.
Her heartbroken parents Lisa and Steve said Ellie's death was 'something no parent ever imagines'.
Mrs Taylor-Ward, 43, said she and her husband were baffled over Ellie's sudden death.
She said: "People with asthmatic children know the warning signs and know what to look for. Ellie was fine that day, she had no problems with her breathing. There's nothing anyone could have done."
Ellie was diagnosed with asthma as a toddler and suffered from several allergies as well as severe eczema, which once so severe she was put into isolation at Sheffield Children's Hospital.
Mr Taylor-Ward, said: "She had good days and bad days. She used an inhaler. Her asthma had been really well-controlled."
Ellie had been out shopping with her mum on the morning before her death, then went to visit boyfriend Bradley Haythorne, 18, at about 1pm.
Her grieving father said: "Just before 5pm, Bradley phoned, saying she was having an asthma attack.
"I jumped in the car and went around, he only lives about 10 minutes away.
"Bradley was in his bedroom and Ellie was on the bed. She was unresponsive and blue. I was panicking, but I did CPR until the paramedics turned up.
"Bradley said his mum was putting their tea out and they had got two cans of pop in the bedroom which Ellie went to fetch.
"When she didn't come down he went looking for her - that's when he found her."
The family had an agonising wait at the hospital as medics struggled to resuscitate Ellie.
Mrs Taylor-Ward said: "We knew she had gone. It was just devastating, so heartbreaking. We were allowed to go in to see her. We stroked her hair, held her hands and gave her a kiss. We told her we loved her."
Ellie's funeral took place at Christ Church, Sheffield, followed by burial at the city's Intake Village Cemetery. Her favourite songs were played, Steve and Bradley read poems and friends prepared a special eulogy.
Her mum said: "We have to carry on for (our 14-year-old son) Luke, as he's in the middle of exams as well. Ellie's death was so sudden. I just know she didn't suffer."
A coroner's investigation is under way into the tragedy on October 19, and test results are being awaited before a decision is made as to whether an inquest is required.