Hello and welcome to the Forum.
To troubleshoot this problem, I would first tip the plant out of its pot and examine the rootball. The pot should drain well, roots should look healthy, and the soil should be damp but aerated, not soaking wet or bone dry.
Often improving drainage and watering less is the answer, let the soil partly dry out before watering again. Empty the palnt's saucer of standing water.
However also note, peat-based soils can become hydrophobic if allowed to get too dry, they then require soaking to be able to again absorb water. If this is the case, soak the plant in a bucket of water overnight. You may need to weigh down the plant, if it floats.
Light: Aglaonema can survuve in low light, they will grow best in bright indirect light. Near a window, even a north window, should be sufficient.
Fertilizer: Do fertilize all your houseplant on a schedule with a complete fertilizer. Fertilizer can be cut back in Winter if the plants growth slows.