This is the 1776th most frequent Polish word.
wszystkiego
"Everything" or "all."
In this context, 'wszystkiego' is used as a pronoun in the genitive case to refer to 'everything,' commonly used in phrases wishing someone good fortune or happiness.
Życzę ci wszystkiego najlepszego.
I wish you all the best.
Here, 'wszystkiego' again appears in the genitive case as a pronoun meaning 'everything,' related to the negation used in the sentence.
Nie mogłem znaleźć wszystkiego, czego szukałem.
I couldn't find everything I was looking for.
In this sentence, 'wszystkiego' functions as a genitive case pronoun 'everything,' connected to the direct object following the verb.