Ariana Grande will not be able to sing for at least four days after harming her vocals.Ariana Grande has been ordered on vocal rest.The 20-year-old singer was forced to keep quiet by doctors after learning she had fried her vocal cords this week.The star is not allowed to even talk while she tries to get her throat back to normal, according to TMZ.A source told the website that after she performed at the Nokia Theater in Los Angeles on Monday night she "badly strained her vocal chords". Then when she appeared on a radio show on Tuesday she was unable belt out a tune, leaving her devastated.After rushing to a medical expert, Ariana was told to stay mum for at least four days and as a result she has had to cancel several media appearances in America, including The Queen Latifah Show and The Arsenio Hall Show.Her new album Yours Truly recently topped the charts but she won't be able to promote it in person for the time being."First day off in forever... Vocal rest and watching movies in with my best friend @alexaluria dunno what I'd do without her," she tweeted on Wednesday.Ariana was thought to be dating The Wanted member Nathan Sykes after they collaborated on track Almost Is Never Enough, which featured in movie The Mortal Instruments: City of Bones.And it seems she may have the same problem he had earlier this year when he needed an operation on his vocal cords, which has since seen him recover.Ariana denied she was seeing Nathan romantically in an Access Hollywood interview aired on Wednesday."No, no -- we're not dating," Ariana said. "He's the sweetest. He's amazing. I have to say, he's one of the most talented vocalists I've ever heard in my life. And live, all the time, he's like, spot on."