A tough week just got a lot worse for one fallen pop star….

Jessica Simpson has been slammed with a $10 million breach of contract lawsuit over an unreleased workout DVD.

In 2005, the singer filmed a exercise instructional for fitness company SpeedFit, but the shoot quickly took a humiliating turn when Jess allegedly turned up to the studio “tipsy.”

Her manager-father Joe reportedly refused to sign off on the project, preventing the SpeedFit boss Alex Astilean from releasing the DVD.

“Jessica was a mess during that shoot,” an insider revealed in an interview with Radaronline this week.

“They asked her to come back and re-shoot, but she refused, and that’s why she’s facing a lawsuit now.”