Question
I have a new phalaenopsis and about a week after I got it the buds started withering and falling off.
Is this something I'm doing wrong?

Answer
Vicky, I doubt that you are doing anything wrong. There are several possibilities to explain the bud drop but the two main culprits are temperature and root condition.  If the buds were exposed to temperatures below 50 degrees F, either where you bought it, in transport, or at home, this can induce buds drop.  The seller should have protected the plant with wrwpping or otherwise advised you on steps you should take to protect it.  As long as the rest of the plant is healthy, it is possible that the flower spike will generate a branch or otherwise set new buds for you.  The other likely explanation is root rot.  This is due to poor potting mix and/or excessive watering where you got it. Some orchids are sold in sphagnum moss which can also cause root rot.  For now, let's assume the bud drop is temperature related (you may be able to confirm that).  If so, just be patient and see if the plant generates new buds.  Go easy on the watering in case there is a root problem.   Drier is better than wetter.  Ultimately, unless the plant was freshly repotted in orchid potting mix, you will need to do this.  It is generally recommended with phalaenopsis after each flowering.