WHEN “The Sopranos” comes back on Sunday night, it will be two years later in the story.

As you might have guessed, much has happened between 2005, when the storyline ended last June, and 2007, when the new episodes pick up the tale.

The characters will fill you in pretty quickly on developments in the ensuing two years.

We aren’t giving anything away – but the first couple of episodes this year will have all but the most devoted fans scratching their heads to recall people and events that happened in past seasons.

In true “Sopranos” style, the dialogue comes at you pretty fast and some viewers are in jeopardy of being left behind.

Who can re member every thing, right?

So here are four critical things from past “Sopranos” seasons that you will need to remember to get the most out of the last season of the legendary series, which is set to begin this Sunday night at 9 on HBO.

KILLING OF BILLY LEOTARDO (SEASON 5)

Remember this? Phil Leotardo (Frank Vincent) never did get the revenge he sought against Tony Soprano’s cousin, Tony Blundetto (Steve Buscemi), after Tony B. killed Phil’s brother, Billy (Chris Caldovino), two seasons ago.

Reluctantly, Tony Soprano (James Gandolfini) whacked his cousin himself rather than leave him to Phil who had planned a long and painful death for his brother’s killer.

That was the end of an unfortunate chapter. Or was it?

NEW HOUSE FOR BOBBY & JANICE (SEASON 6)

Maybe you forgot this: In an episode that aired last May, Tony persuaded the imprisoned Johnny Sack – badly in need of money to pay for his legal defense – to sell his huge house in suburban New Jersey at half price to Tony’s sister, Janice (Aida Turturro), and hubby Bobby Bacala (Steven R. Schirripa).

JANICE’S DEAD BOYFRIEND (SEASON 2)

In one of the most shocking turns of events in “Sopranos” history, Janice shot her boyfriend, Richie Aprile (David Proval, right), to death in Season 2. He’d slapped her during an argument and Janice, without a blink, blew him away at the kitchen table.

Janice, ever the Soprano, never gave the murder a second thought. Right?

A.J.’S NEW GIRLFRIEND WITH BAGGAGE (SEASON 6)

Speaking of relationships, you may have forgotten that Anthony Jr. had found true love in the last “Sopranos” episode last June – a Puerto Rican named Blanca Selgado (Dania Ramirez).

Her heritage was enough to make Tony and Carmela nervous. Imagine how much it helped matters that she also had a young son from a previous relationship.