Assuming you have a Phalaenopsis orchid QP, I make it a practice to never ever trim roots that are alive or leaves that have some green color. If they are all yellow, those are not coming back, those you can trim.
An image would allow us to confirm!
Keys to Phalaenopsis growing:
No direct sun, none! Just a bright spot.
Never let them stay bone dry for very long. Generally water every 4-5 days.
Temperature range of 65-85
Fertilize 4 times a year.
They are epiphytes and need to be repotted at a minimum of every two years. If you don't the potting material can break down, holds too much moisture, and kills roots. Orchid roots need air to survive. No potting soil.
Acceptable media includes fir bark, Orchiata bark, charcoal pieces, perlite pieces. Either straight or in a mix.
Clay pots or plastic.
Never grow it double potted as in a plastic pot inside of a ceramic pot.
All containers need drainage holes.
Orchids are not really the prettiest of plants. Trimming leaves and roots are cosmetic things and NOT good for orchids! By trimming those things you could have a pronounced effect on flower production in terms of both numbers and size.
Phalaenopsis generally bloom from late December through early April.
They are easy to flower in general but some finicky plants can be enticed into flowering by giving them a 15 degree night time temperature drop for 2 weeks in the Fall. These guys might not bloom if it is always 68-72 degrees.
