But the “mein” is there and I wouldn’t call it a pronoun in this case. If it’s used before a noun like in “mein Geld” then it’s just a possessive determiner.
Determiners are a more general class of words that include for example articles. Mein is not acting as a pronoun in the example sentence but more like an article.
It’s missing the verb and I’m not sure which pronoun you’re missing.
Grammatically correct would be “Wo ist mein Geld?” The “mein” is The missing pronoun.
But the “mein” is there and I wouldn’t call it a pronoun in this case. If it’s used before a noun like in “mein Geld” then it’s just a possessive determiner.
Since I have no clue what the latter is I sadly can not say if this is the case or not.
Determiners are a more general class of words that include for example articles. Mein is not acting as a pronoun in the example sentence but more like an article.