Watch Alvin and the Chipmunks: The Squeakquel (2009) <- click

Alvin and the Chipmunks: The Squeakquel (2009) is a wonderful movie.
If you wish to see the movie, just click the title and you`ll see it. BTW,it has romanian sub
So here`s the plot:
During the Chipmunks' benefit concert in Paris, France, Dave (Jason Lee) is badly injured after a falling billboard sends him flying across the stage into electric devices.

After the accident, Dave is rushed to the hospital. Even though he survives, he must stay to recuperate, leaving Dave’s Aunt Jackie to look after the Chipmunks, while arrangements are also made for them to go to school.

Arriving at an airport, the Chipmunks meet up with Jackie, who introduces her grandson, Tobin "Toby" Seville (Zachary Levi). After Jackie falls down a staircase and a luggage trolley crashes into her, she, too, is sent to a hospital, leaving Toby in charge.

Meanwhile, Ian (David Cross) now lives in the basement of JETT Records. A FedEx truck comes around the corner, and a package falls out. Three singing female chipmunks, Brittany (Christina Applegate), Jeanette (Anna Faris) and Eleanor (Amy Poehler), who call themselves the Chipettes, emerge from the package and introduce themselves to Ian. Brittany says that since Ian made the Chipmunks stars, they want to be stars, too. To prove their talent, they sing "Put Your Records On," and Ian hires them.

During their first day at school, Alvin, Simon and Theodore catch the attention of the females in their class. The jocks grow jealous, physically bullying them and resulting in all parties being sent to the Principal Office. There, they discover that the Principal, Dr. Rubin, is a huge fan of the Chipmunks. She consequently asks the Chipmunks to save the school’s music programme by representing their school in the Battle of the Bands in exchange for not suspending them. The Chipmunks immediately accepts. Meanwhile, when Ian receives the daily newspaper, he is shocked to find the Chipmunks on the front page. After he reads the story, he quickly sends the Chipettes to school (just to get the winning money).

Tension between Alvin and Simon develops as Alvin begins socialising with the jocks of the school, but the one who is most affected is Theodore, who believes he is losing his brothers because they are fighting all the time.

When the Chipmunks meet the Chipettes, they gain crushes on their counterparts, but are soon forced to have a rivalry after discovering that they are with Ian. The Chipmunks and the Chipettes compete against each other in the Battle of the Bands. During lunchtime, Alvin meets up with Brittany, sharing a slightly romantic moment with her until he warns her about Ian’s past. Brittany leaves, not believing him.

At a concert, the Chipettes sing "Single Ladies (Put a Ring on It)". Ian videotapes the Chipettes performance and posts it on YouTube, along with his phone number. The Chipettes win the competition and Ian becomes rich and famous again. Simon and Theodore had been forced to forfeit the competition when Alvin failed to show up, and at home, Simon and Theodore ignore him. The embarrassment is too much for Theodore, causing him to run away to the zoo, where Toby and the boys find and save him. This brings out the best in all four of them and the Chipmunks forgive each other.

Soon, the Chipettes are hired as the opening act at a Britney Spears concert at the Staples Centre. Unfortunately, the concert is on the same night as the school concert, so Ian decides to blow off the battle and make the Chipettes perform at the concert. However, Brittany refuses Ian’s command to sing without her sisters, so Ian threatens to barbecue them at a restaurant if they don't.

At the school, the Battle of the Bands is approaching. Alvin gets a phone call from Brittany, saying that she and her sisters have been imprisoned in a cage. Alvin races to save them on his motorbike while Simon tells Jeanette how to open the cage on the phone. The Chipettes escape the cage, climb out of the limo, and jump onto Alvin's bike, with Ian in pursuit.

While being chased, Brittany apologizes to Alvin. Ian pursues them with a remote control helicopter, but fails, and Alvin and the Chipettes arrive at the contest just before Simon and Theodore forfeit. All chipmunks sing "We Are Family" and the school wins $25,000.

At the Staples Centre, Ian attempts to impersonate Brittany while singing Single Ladies. He is booed off by the crowd and taken away by the security guards.

Back at the school, The Chipmunks and Chipettes sing ‘Shake your Groove Thing’ and all of the students dance. The Chipmunks go back home with a recovered Dave while Toby goes back home, and the Chipettes are adopted into the family. When Dave wishes them good night and turns the lights off, Alvin turns them back on repeatedly. After Dave trips over a skateboard, Alvin wishes him good night and turns the lights off.

The post credits show the jocks cleaning breaches with Dr. Rubin watching them.

An epilogue shows Ian being thrown into a dumpster backstage by the guards.