Shane Fox, 26, was murdered near his flat in Nest Farm Crescent at about 2am on December 1 last year but despite four arrests nobody has been brought before the courts.
It is Northamptonshire Police's only unsolved murder in the last two years.
His mum Caroline said: "Somebody knows who he is. Somebody knows what he's done.
"Come forward. Help us. Help us get justice for Shane. We can never move on properly until we have answers."
Shane's dad Ian said he cannot face celebrating Christmas. He said: "Every year is going to be the same. We are putting a false face on all the time."
Caroline said: "It's like you're dead inside. You're just going through the motions.
"It's like someone has grabbed your heart and ripped it to pieces and every time I come around the corner from work my heart aches all the time.
"It's just horrible. I just miss him, I miss him so much."
The former Weavers Academy pupil, described as a "big softie" by his parents, had been out with his brother Craig when he was attacked.
Earlier that evening the pair had walked around Nest Farm Crescent, over the bridge and into town before heading back. They were boisterous and made noise as they went over the bridge near Well Cafe, causing someone to shout out from their flat.
As they went round the corner Craig, who was about 20 yards behind his brother, witnessed his brother being fatally stabbed. Craig was also stabbed and was left with minor injuries.
The suspect is described as a black man in his 20s, with a round face and wearing a dark puffer jacket with horizontal stitching.
Detective Chief Inspector Joe Banfield, the senior investigating officer, said: "A year on we are very much looking for anybody who might knowing anything or who might not have felt able to come forward at the time, to come forward now and tell us what they know.
"Any small bit of information might be a key part of the jigsaw that we don't know about and might help us take this forward to a positive conclusion for Shane's family."
Shane, who collected scrap, was described as "cheeky" and a man who "loved to party".
He grew up on the Queensway estate before moving to the Hemmingwell estate about two years ago. He was "chuffed" with the home he had started to build up.
He had planned to propose to his girlfriend on holiday and left behind two young children.
Caroline shared stories of how Shane would begrudgingly help her put Christmas decorations up and come round to raid the fridge for a sausage roll. He would always give his mum a kiss on the cheek.
Dad Ian said: "If we were having a bad day or were worried about anything and were down, within five minutes of him being there he would turn it around."
Caroline and Ian's heartbreak was made "10 times worse" after Shane's body was not released in time for Christmas as promised, meaning they could not bury him until January 11. Caroline said this robbed her of saying a proper final goodbye.
A team of 12 police officers, as well as regional resources, are still working to try and piece together who murdered Shane.
They are appealing for the tight-knit community to come forward with information about the senseless murder, particularly two potential witnesses.
Det Ch Insp Banfield said: "There are three people we are trying to trace. One is the suspect and two others we are treating as witnesses who we want to come forward.
"One is the person on the very grainy CCTV at the Well Cafe. The CCTV was taken at about 1.55am and the incident happened at about 2am, so that person was at the Well Cafe at or around the time that Craig and Shane were walking back from town and when the suspect might have been hanging around.
"The other person we are looking to speak to is a person who knocked on Shane's door at about 9pm on November 30. They shouted, trying to get hold of Shane. He didn't get hold of him and we would like to know why that person was there, who they were and whether they might know anything about the motivation for this attack."
This man is described as being white, about 5ft 7in to 5ft 8in, with a slim build and a bald head, and was wearing a blue short-sleeved T-shirt and dark blue jeans.
A £10,000 reward is still active for information that leads to the arrest and conviction of the person responsible as part of Operation Talbot.
Ian urged anyone with information to contact police on 101 or Crimestoppers anonymously on 0800 555111.
He said: "If someone knows who has done it, how would they feel if it was one of their children?"
No further action has been taken against three of the men, aged 39, 36 and 22, arrested during the course of the investigation.
A 27-year-old man arrested in July was released under investigation pending further inquiries.
Caroline described Shane's attacker as "evil".
She said: "He's got no conscience, no morals, and the person who knows is just as evil to hide that.
"He could do it again. If he can to it Shane and stab Craig, he could do it again."
Shane's parents said they won't rest until their son's murderer is caught.
Christmas lights were put up outside their house the year Shane was murdered and have not been turned off since.
Caroline said: "They won't be turned off until we get justice."