Hernandez was last seen on Dec. 7.
Friends reported her missing the next day when they had not heard from her.
The Fresno County Sheriff's Office says her disappearance is suspicious.
"There's something that's definitely gone wrong and again we're looking for answers at this point," said Tony Botti with the Fresno County Sheriff's Office.
He says the investigation is active even though a full month has passed.
For Missy's family - each passing day feels like an eternity.
"I have felt very anxious, worried that she's out there somewhere and she needs help," said Daisy Hernandez, Missy's sister.
Daisy lives in Texas, but recently came to Fresno to search for her sister.
She also put up flyers, making sure people know Missy is out there somewhere.
Friends and family say she was popular and got along with everyone, that's why they're shocked that she disappeared without a trace.
"We are wanting her to come home. We need answers. I think we all deserve to know where she is at or what happened," said Daisy Hernandez.
The sheriff's department is also searching for answers.
"We're never going to give up. We're going to continue to seek out people to get information that's going to bring us the answers we need so they can hopefully move forward," said Hernandez.
The sheriff's office is urging anyone with information about where she is to contact Detective Gary Haslam at (559) 367-4734, (559) 600-8209, or the dispatch center at (559) 600-3111.