Old printer seems not working fine

Im use this thing a lot,and then today i suddenly get the "paper stuck inside the printer" error but there is no paper in the tray

I tried to open it up,not a single piece of paper in there

Then i tried to restart the printer,it keeps showing the same error,but i hear the sound in the printer like the paper roller roll slowly and then it fastly rolling then it stopped and it shows the same error on the screen

Do everyone have any solutions? Btw the model is Pixma G1000