Today's day of action sees a different child's appeal and photo posted on Twitter every 30 minutes under the hashtag #bigtweet.
Police have called off their search for a missing mum of three after finding a body in a field in Burscough.
Concerns are growing for a 15-year-old girl and her baby son who have been missing for five days.
Police are trying to trace a 12-year-old boy who went missing from his home more than 48 hours ago.
Rochaan Cookhorn was last seen in the Buckstone Road area of Edmonton, north London, at 6pm on Friday when he left the house with a group of friends.
Scotland Yard said it was "out of character" for him to be missing for so long and officers are increasingly concerned for his welfare.
Rochaan is black, 5ft 7ins and has short black hair. When he was last seen, he was wearing a red vest top, blue jeans and black trainers.
Anyone with information on where he may be is asked to call police on 020 8345 3332 or 101.
The mother of a British man who has gone missing in the Malaysian jungle has called on the authorities to do more to search for him.
Gareth Huntley, 34, from London, has not been seen since he went on a trek to visit a waterfall in Tioman Island, off the south eastern coast of the country's mainland, on Tuesday morning.
He told friends at the headquarters of a nearby charity project where he was volunteering that he would return by 2pm the same day but failed to come back.
His mother, Janet Southwell, said: "At this stage I feel it is essential that the search be intensified as time is running out for Gareth, so I would really appreciate the support of the Malaysian authorities and the UK government with this."
A mental health patient who has been missing from a care unit in Chichester for more than a day should not be approached by the public, police have warned.
Jason Merriman, 43, is a compulsory patient at The Oaklands Centre for Acute Care in Chichester, West Sussex. He went out on unescorted leave at 12.45pm on Friday and has failed to return, a Sussex Police spokesman said.
Inspector Robert Moore said: "Jason's behaviour may be erratic and irrational due to his mental condition."
Mr Merriman is white, 6ft 2in, broad, with short brown hair. He was last seen wearing a dark blue long-sleeved sweatshirt, green camouflage trousers and black training shoes with white socks.
He has links across the south coast including Chichester, Southampton, and Brighton, and he might visit the Isle of Wight, the spokesman added.
Police say they received a number of calls from the public with information following the disappearance of 13-month-old Lola Page, who has now been found.
Detective chief inspector Matt Markham from Force CID, said: "We are pleased to say that Lola is now returned to a place of safety and she is doing well.
“We want to thank the public for their assistance with this appeal. We received a number of calls from people with information, who were keen to help.”
Lola's mother, 18-year-old Stacey Ball and three other men have now been arrested in connection to the child's alleged kidnap in Walsall.
Missing baby Lola Page has been found "safe and well" in Walsall.
Police have arrested four people in connection with the alleged kidnap, including the child's mother, 18-year-old Stacey Ball and another man, who were both found with the 13-month-old at an address in Willenhall, West Midlands.
Ms Ball is accused of kidnap, while the other man is accused of assisting an offender.
Shortly after, officers arrested two more men on suspicion of conspiracy to kidnap. All four are in custody and will be questioned later today.
Police have released descriptions of missing baby Lola Page and her mother after the child was taken from her foster parents.
Lola is described by police as white with short straight blonde hair and was wearing a white cardigan and blue polka dot dress when she was taken.
Her mother Stacey Ball is described as white, of thin build and was wearing a long black wig, black leggings and a black and tan patterned dress when she left with her daughter.
A mother who took her one-year-old daughter from a foster family who were caring for the child is being sought over concerns for the baby's welfare.
West Midlands Police said they were concerned for missing child Lola Page after she was taken during a supervised visit in Willenhall in the West Midlands just before 1pm yesterday.
Mother Stacey Ball, 18, of Walsall Wood, is believed to have got into a dark-coloured car with her child which was then driven off, after leaving the address.
There have no sightings of either the child or Ms Ball since the pair went missing, police said.
Police have appealed for information after a 16-year-old girl went missing from her home in Leytonstone, in London yesterday afternoon.
Aiesha Sharif was last seen going in to Aldgate East Underground station at 4.30 pm on February 14. Police believe she may be in the south London area.
She was last seen wearing a long, black Jilbab dress, a light brown headscarf, a light brown coat and was carrying a cream handbag.
The Missing People charity has appealed for information on two people who went missing in separate incidents in Yorkshire in January.
Volunteers from the charity attended today's game between York City and Cheltenham Town to help find Megan Roberts, a 20-year-old student attending York St John University, and Edward Machin, 39.
They both went missing on 23 January.
Miss Roberts was last seen near a bridge over the River Ouse. Police said the most probable scenario was that she "entered the river" while "heavily affected by alcohol".
Mr Machin was last seen in Bempton, near Bridlington, after he made a journey by taxi.
Fans at the game were are also reminded about missing York chef Claudia Lawrence, who was last seen in March 2009.