my 2002 mazda is stuck in fourth gear(standard)?

[its12gage]

i have a 2002 mazda protege 5...i recently got stranded at a light because the car would no longer go in to first gear i then realized that the car is permanetly stuck in fourth gear...i can move the shift knob to any gear but it wont drive....when i was driving down the highway because i had to get it home i noticed i could move the shift knob from 3rd to neutral to fourth and nothing changed it was still driving in fourth gear...i hear it could be a shift fork but i dont think so.i got under the car and messed with the bar that goes from the shifter knob to the tranny and manually put it in neutral but when i started it the car was still in fourth gear....im really stressed i need help