Too Much Rain or Water
We all have overwatered and that is where our downfall starts. Don’t beat yourself up but quickly make changes. First, pull your orchid carefully out of the pot and check to see if the roots are wet way down deep inside the pot. If so, put your orchid out in a big pot, a big bowl or something where it can get air. You may save it if you do this right away. Let the roots completely dry out. Do not throw away an orchid if it is overwatered, turns yellow, and drops leaves, there still is a chance you can save it.
After making sure it is all dried out in the roots, remove the yellow leaves, check the roots and only clip 1/3 of the roots off if they are no good. Good roots will often come back. Bad roots have breaks in them and you can pull the outer covering of the root off. Leave 2/3 of the best roots. Put the plant in a net pot, fill it lightly with large media, leca, charcoal, and put about an ounce of sphagnum moss around the roots. Water it lightly, set up and do not bother it for one week. Water lightly and repeat, one week each week. If you see new stems or leaves popping out, you know you will have a beautiful orchid again. Definition of water lightly, put in the sink, dip it in up to the top of the root ball while still in the pot, do not put water on the crown (crown is where roots meet the stems), and let sit for one minute. Remove, drain, put pot up. Once a week should work for most ill orchids.
We often throw away plants too easily. They have life in them still and even when you cut too many roots you may still be able to save the plant. If you stop watering, this will completely kill all plants. Take care and enjoy. Treat them like you dogs or cats, they need love, water, and food.