When Héctor asks for Chicharrón for his guitar, Chicharrón demands Héctor to sing Chicharrón's favorite song, "Everyone Knows Juanita", in exchange for the guitar. While Héctor finishes the drink he shared with Chicharrón to honor him, Miguel is astonished by Chicharrón's disappearance, but he agrees to use Chicharrón's guitar in the contest.
When Héctor and Miguel arrived at the contest, Miguel wants to sing "Remember Me" with the guitar but Héctor doesn't want him to sing it so instead, Miguel sings the musical number "Un Poco Loco" on stage along with Héctor.
After the contest, however, Miguel ditches Héctor to look for Ernesto on his own. Taking the guitar with him, Miguel tries to get to Ernesto's Mansion. After the security guard by the tram refuses to let him in, the band Los Chachalacos, who became the winners of the contest, arrive and help sneak Miguel into the party without getting noticed by the guard. Once inside the mansion, Miguel gets his idol's attention by playing the guitar and singing a song; however, Miguel slips and falls in the pool. Ernesto saves Miguel from the pool, but he doesn't pick up the guitar and leaves it there.
This guitar was Chicharrón's prized beloved guitar.
The guitar has a writing inside of the body which is probably the brand name for it.
The guitar strap for this guitar is the same one that Miguel use to carry his toolkit.
When Chicharrón is starting to being forgotten he couldn't even play his guitar if he wanted too.
This guitar hasn't been seen in the rest of the film because the guitar is either still in the pool, or someone went into the pool and reused it.
Chicharrón refuse to let Héctor have his guitar
Héctor strums the guitar
Héctor play the guitar while singing to Chicharrón
Miguel starts to strum the guitar
Notice that the guitar has the writing inside the body.