1990 Toyota Camry transmission won't go into any gear

You didn't make clear you have a automatic trasmission or manual?
if is a manual trasmission you have to look the clutch and to valves that is puting the trasmision oil pressure to move the clutch one at the end near the gear box and the second after the clutch pedal outside of the cabin imediatley after the pedal. you have to look to the oil level in the rezervoir, if you dont have the problem to bay some oil and to change completely the oil first maybe the right solution to begin with oil change first , may be is freeze from the dirties finded in the oil pipes and valves.
if you have the automatic trasmission sorry i dont know, because the problems there are more complex.