。
Where's my chocolate?
Literal
I [of-の] chocolate [topic-は] where is.
Casual masculine どこだ ('where is it') drops the polite copula ですか for the bare だ — direct, slightly gruff, very natural in male speech. The childlike complaint in tone — 'where'd my chocolate go?' — fits a kid or casual male speaker rummaging through the kitchen. チョコレート is one of many everyday loanwords from English; the abbreviated チョコ is even more colloquial.