Alison was never dead. She apparently has a twin sister named Courtney who lives in a mental hospital because she pretends that she is Alison. One day, while Courtney was visiting her house, she pretended to be Alison, and her parents believed her. So Alison was sent to the asylum by mistake. When Ali came home she found Courtney sleeping in the barn with her friends. Ali got so mad that Courtney had done this to her that she killed her, then went back to the asylum and pretended she was Courtney. The texts really were from Alison, and she had Toby spy on them so she knew all of their secrets to scare them because she was mad at them for not realizing that they were hanging out with Courtney after all.
P.S. If this is wrong it's because I was told all of this by my friend who claims to have read the series.
it was her stalker
She's not dead.
Yes because A killed him
Ian gets killed by "A" but later his body disappears
she knows who killed ali and that her boyfriend is still alvive
"A" killed him
No
A
'A' in Pretty Little Liars is alive at the moment in the show but later gets killed by Spencer.
He wasn't.
Alison.
it was her stalker
Ali killed Ali!
because she is A.
alison did
She's not dead.
"A" killed him