How did Alison actually die on pretty little liars ? (I know it was not filmed, but I am curious.)

At least in the books, Alison didn't die. Courtney, her twin sister died after being suffocated and put in the hole in the ground. The real Alison came back to get back at the girls.

According to the evidence she was hit in the head with a shovel and supposedly she was buried alive.

i'd say sufferocated and buried

Actually she was murdered cause they found the body.

well accually she didn't die because of the bat/shovel if te watch the t.v mostra te heard the lil boy seth say "It must have been horrible what happened to your friend,getting dirt shoved into her lungs I can't even handle sand in my mouth."Soooooooooo someone shoved dirt down her lungs u get it now?

A killed her

Well noone knows if Ally is really dead o if she is alive. If you`ve watched most episodes, then they mostra Ally (or it could be her twin sister) several time. Even some of the main charactes (Aria, Hannah etc) Have detto they`ve seen her. Ally died of murder.