Inspect the orchid roots. Healthy orchid roots look white, firm and fleshy. Overwatered orchids have mushy, brown roots. Snip off the bad roots and try repotting the orchid. Toss the orchid if the main portion of the orchid plant -- the place that connects the roots to the leaves -- looks mushy.
Inspect the orchid leaves. Healthy orchid leaves look dark green. Withered orchid leaves are considered normal when replaced with new leaves; leaves only live about three to five years. Yellow leaves indicate that the plant doesn't receive enough sunlight, is going into dormancy or is in the process of dying.
Water the orchid until the top 1 inch of soil in the center of the pot is wet, but not soggy. Wait until the soil slightly dries, normally after a few days, and then water again. Keep the area around the orchid slightly humid with a mister, or by positioning the orchid near other potted plants. If the orchid doesn't grow with regular watering, it might be dead.
Place the orchid in a south-facing window where it receives adequate light. Dust off the leaves with a soft damp cloth to ensure the plant can receive the most amount of sun. If the orchid doesn't grow with adequate sunlight, it might be dead.