This is an irregular verb. It follows the conjugation pattern of the verb parecer.
PresentPresente
El sol desaparece detrás de las montañas.
The sun disappears behind the mountains.
PreteritePretérito indefinido
Mis llaves desaparecieron de la mesa.
My keys disappeared from the table.
ImperfectPretérito imperfecto
Cuando era pequeño, mi gato desaparecía durante horas.
When I was little, my cat would disappear for hours.