Learn Farsi: او متوجه مشکل نشد. - She didn't realize the problem.

The verb here is شدن (to become). Its past stem is شد. To make it negative, we add the prefix نـ (na-) to make نشد. Because the subject is او (she/he), we don't add any extra personal ending. In the simple past, the third-person singular always has a hidden or 'zero' ending.

Why are there two words, متوجه and نشد, for 'didn't realize'?

Farsi uses a lot of compound verbs. 'To realize' is متوجه شدن (literally: to become aware). When we change a compound verb into the negative past tense, we only change the second part (شدن becomes نشد). The first word, متوجه, stays exactly the same.

Is there a hidden sound between متوجه and مشکل?

Yes! There is an invisible 'e' sound (called the Ezafe) linking these two words, so it is pronounced 'motevajjeh-e moshkel'. This links the adjective 'aware' to the noun 'problem', working a bit like the English word 'of' in 'aware of the problem'.

Does او always mean 'she'?

No, the pronoun او is completely gender-neutral and means both 'he' and 'she'. You only know it means 'she' in this sentence because of the outside context of the conversation. The English translation provides 'she' just as a working example.