Bach's car was found Friday morning in Wheeler, Indiana, right next to Hobart. Police say they want to talk to one of her friends.
"She is the sunshine of my life," said Sandra Bach, the missing girl's mother. "She's beautiful. Amanda, please come home if you're out there."
It is an emotional plea from the parents of Amanda Bach just days after the Portage teen went missing.
"We're all after one goal, that's to get my daughter back," said Bill Bach, the missing girl's father.
The 19-year-old was last seen leaving her home to visit a friend around 10 p.m. Thursday night. Her family says they became worried when she missed her 1 a.m. curfew.
"The last thing I did with her and my dad was watching TV," said Sarah Bach, the missing girl's sister. "We were talking and stuff."
Bach has not been heard from since -- although, the 2006 gold Pontiac G6 she was driving was found a few hours later.
Witnesses say the car had a flat tire, the driver side door was open and the keys were in the ignition. Bach's belongings were also in the vehicle, but her cell phone was not.
Saturday afternoon, Amanda Bach's friends and family, along with some people from her Facebook community, frantically looked for her.
"This could be our friend, our daughter. We owe it to her and her family to be out here," said searcher Cora Anderson.
The search is likely to move further south toward the town of Wheeler, where Amanda Bach was last seen alive. That's where authorities say the friend she was visiting lives. He has since left town.
Saturday, police called the friend a person of interest in Bach's disappearance.
"They're trying to get a hold of him and get him back in town to question him," said Porter County Sheriff's Sergeant Larry LaFlower.
Amanda Bach is described as 5-foot-2-inches tall, weighing about 105 pounds. She has brown eyes and brown, below the shoulder length hair. She was last seen wearing a long-sleeved gray shirt and black capri-style pants.
Relatives say Amanda would never just leave.
"My belief is that something bad happened to her," said Sonya Cepedes, the missing girl's aunt.
But her family is hoping for Amanda's safe return.
"She needs to come home," said mother Sandra Bach. We need to bring her home."
Bach graduated from Portage High School in June and had plans to go to college.
The Indiana State Police and the FBI have now joined in the investigation to find Amanda Bach.