Insufficient light is one of the most common reasons for failure to bloom or re-bloom, according to the American Orchid Society. Orchids need bright, indirect light to bloom. The best way to determine if your orchid is getting sufficient light is to inspect the foliage. Orchids with deep-green foliage aren't getting the light they need. The American Orchid Society advises orchid growers that a healthy orchid has light, grass-green foliage if it's positioned in the appropriate place and light.
Orchids need a difference in temperature between day and night. If they aren't getting it, they may not produce buds. The average temperature for most orchids is 80 to 85 degrees Fahrenheit during the day and 60 to 65 degrees Fahrenheit at night. If the temperature consistent in the orchid's current location, consider moving it. And don't guess the temperature; use a thermometer and do your best to provide the proper conditions.
If your orchid won't bloom, It's possible that you've chosen an orchid that's inappropriate for your conditions. Not all orchids are suitable for houseplant culture and require greenhouse-like conditions. Beginners should stick to Cattleyas or Phaelenopsis orchids, which tolerate indoor conditions well and are a nice introduction to orchid culture. Also, take a second to consider the source of the orchid. It's best to buy from reputable growers who can provide information on the plants. Contact a nearby orchid society and ask some questions.
Orchids have earned a reputation for being difficult to grow, but that's usually because most growers can't or don't provide the conditions they need. Follow the orchid's requirements to the letter. Skimping, slacking or failing to take the steps necessary to satisfy the orchid's needs will kill the plant. Provide the light, potting media, humidity, watering and fertilizer that your particular orchid needs.