Sketch of Lindsay Lohan in court on April 22
Bill Robles/Splash News Online
04/24/2011 AT 06:00 PM EDT
04/23/2011 AT 10:20 PM EDT
It's been a rough couple of days for Lindsay Lohan
The actress returned to Lynwood Jail on Friday after a topsy-turvy day in court
, and she is frustrated with the status of her jewelry theft case.
"She is fine," says producer Nathan Folks, who is a close friend of Lohan, 24. "Obviously, she is upset about [being sentenced to four months in jail]."
On Friday, a judge found Lohan, who is accused of stealing
a $2,500 necklace, in violation of probation and sentenced her to the jail time and a hefty 480 hours of community service, which Folks admits was a "setback."
But she was allowed to post bail and released within hours of getting booked. Lohan remains free pending an appeal of the sentence, which legal experts say she has slim chance of winning.
"She is angry because she has been working so hard on turning her life around," says Folks, who insists Lohan is clean and sober. "She didn't do what they said she did. She didn't steal that necklace."
Still, Lohan is resigned to accept whatever decision comes down from the court when her trial begins June 3.
"She is ready to do her time. She wants to go to A.A. and N.A. and to serve her [more than] 400 hours [of community service]," Folks says. "She has already been doing lots of charity work."