Desmadre is a very common and versatile slang term in Spanish, particularly in Mexico, that means 'mess', 'chaos', or 'disorder'. It can refer to a chaotic situation, a wild party, or even a person who is a bit of a mess themselves.
In the song, the singer apologizes, saying, "Sé que estás cansada que mi vida sea un desmadre" (I know you're tired of my life being a mess). Here, it implies his life is disorganized, perhaps wild, or full of problems, which has pushed his loved one away. It's an engaging word that captures a relatable human experience.
The man singing has been drinking since the day before — "Ando tomando desde ayer" ("I've been drinking since yesterday") — and it is doing the opposite of what he hoped: "Con cada trago más te clavas en mi cora" ("with every drink you dig deeper into my heart"). The woman he wants "no quiere nada conmigo" ("wants nothing to do with me"), so he picks a fight with the only culprit left: "La neta traigo atravesado a Cupido" ("honestly, I've got a grudge against Cupid"). Nothing gets through to him — "Ni con un payaso me sacan una sonrisa" ("not even a clown can get a smile out of me").
The chorus is the plea itself, and Grupo Firme let him make his case badly. He tells her the doors are still open — "De mi casa y de mi corazón tienes las llaves" ("you have the keys to my house and my heart") — apologises for phoning at all ("sorry que te llame"), then names the reason she left without claiming he has fixed it: "Sé que estás cansada que mi vida sea un desmadre" ("I know you're tired of my life being a mess"). It ends on the one word of the title, "Vuelve" ("come back") — and the song has already said how that goes: "Y tú no vuelves" ("and you don't come back").