Learn Italian: Non è colpa mia, non ho potuto fare niente! - It is not my fault, I couldn't do anything!

When a modal verb like potere (to be able to) is in the passato prossimo, it usually borrows its helper verb from the action that follows it. Because the main action here is fare (to do), which takes avere (as in ho fatto), the modal verb also takes avere. That is why we say ho potuto fare.

What would happen to ho potuto if the action was a motion verb like andare (to go) instead of fare?

Since andare takes the helper verb essere (as in sono andato), the modal verb would switch to match it. You would instead say non sono potuto andare (I couldn't go). Because our sentence uses fare, it stays with avere.

Why is the word order colpa mia instead of la mia colpa?

Usually, possessive words go before the noun with an article, like la mia macchina. However, in fixed everyday expressions about blame, such as è colpa mia (it is my fault), the possessive adjective always goes directly after the noun and drops the article.

Why are there two negative words, non and niente, in the second half?