Former NY Mets and Philadelphia Phillies player Lenny Dykstra had his private jet repossessed by creditors…and now he’s demanding it back, claiming they violated a court order.

Dykstra filed papers in U.S. Bankruptcy Court in California yesterday stating that 3 creditors — Constant Aviation, Classic Interiors and Crystal Air Aviation — violated a court order and took possession of his Gulfstream jet. It’s unclear when the plane was actually taken.

He claims a judge had granted him an “automatic stay” … which means even though he may be in debt, his property was temporarily off-limits.

Now, he declares in the docs that “the airplane must be returned” … and he wants an $800,000 check to boot.