Hi Rara, and welcome to the forum!
Don't panic! Flowers can drop for lots of reasons - many rather harmless.
While the flowers are lovely, the plant is the first priority. A healthy plant can lose its flowers and still bloom perfectly next year.
The first thing to consider is whether your 'pot' has drainage. I'm seeing many florists and chain stores selling orchids in attractive vases that have no drainage. That's a sure problem! If that's the case, then yours needs to be repotted ASAP. It's not scary, and we can help, but I'm not going to get into it now.
If the flowers have been open a while, they may just be dying back. If the ones closest to the stem are fading, then it's probably just the end of their blooming cycle.
If most of the young blooms and near opening buds have shriveled, then they done what we call 'blasting.' A change in conditions freaked them out and they gave up the ghost. It doesn't hurt the plant, and you can possibly reinduce the spike to bloom, if the leaves seem healthy enough.
Post a picture if you can - it will help us guide you.