Learn Icelandic: Af hverju saknar þú fortíðarinnar?

The verb sakna (to miss) is one of the verbs in Icelandic that requires its object to be in the genitive case instead of the accusative or dative. Whenever you miss someone or something, that noun must take a genitive ending.

How do you break down the endings on fortíðarinnar?

The base word is the feminine noun fortíð (past). In the genitive case, it takes the ending -ar to become fortíðar. Since the sentence says "the past" rather than just "a past", we also attach the feminine genitive definite article -innar to the end, resulting in fortíðarinnar.

Why is Af hverju used for "why" here, and what case is it in?

Af hverju is the most common way to say "why" in Icelandic, but it literally means "from what". The preposition af always triggers the dative case, so hverju is the dative neuter form of the question word hvað (what).

Why does the subject þú come after the verb saknar?

Icelandic strictly follows the V2 (verb-second) rule. Since the question phrase Af hverju occupies the first position in the sentence, the verb saknar must take the second slot. This forces the subject þú to move after the verb.