Have a 1986 2.5 it will not shift with the motor runing.

Try to check the clutch. Lining must have been worn-out.

Im taking for granted this is a stick if so it is one of two problems you may be out of clutch fluid it is a small ittle resoivar up by the fire wall probably on driver side if thats not it then your syncronazation gears are shot they are little sliding wieghts inside the tranny that align the gears for shifting