It always says paper jam and it has no paper jam

1. Turn off the printer.
2. Remove any paper trays. Inspect them for wrinkled or damaged paper.
3. Also open the back cover of the printer if this model has one.
4. Open any other doors that give access to the printer's paper path and to the toner or ink cartridge.
5. If necessary, remove the toner or ink cartridge. Place it away from light/ sun light to avoid damaging it.
6. If you find a piece of jammed paper, remove it by holding it with both hands and pulling firmly. The goal is to keep the paper from tearing. If several pieces are jammed together, try pulling out the middle piece first to loosen the jam.
7. If the paper does tear, try rotating the roller gears manually to free the paper. Don't force anything, though. Do this step especially if the jam message comes up repeatedly without any obvious paper jam, there may be a small tear of paper inside.
8. Ones the printer is free of paper Replace the toner or ink cartridge and paper trays, close any doors you opened and turn the printer back on.
9. If the printer paper jam message still appears, then there is still some paper in the printer. Reinspect the paper path.
10. see alternative if the problem is still not solved.
    

alternative :
Load a piece of thick paper, for example photo paper and press the resume button (may be diffrent button on diffrent models) a few times to the printer picks up the paper and puts it through the machine.


if the problem remains, some of the sensor / switches might have become stuck or are out of place, or there is still a small piece of paper or something else inside the machine and its coming up as a paper jam.

The machine would need to be taken apart and cleaned to solve the issue.