Not all flowers last forever. We'd never have seed generation if they did. Also something about beauty is enhanced by scarcity.
If your flowers didn't fall off, I'd be concerned.
Based on what I can tell, buy some sphagnum moss and bark chips (or other inert material available to you). Repot your orchid and in about a years time, it will bloom again for you if it gets enough light. Make sure the leaves are a light grassy green color and not dark evergreen.
Report back when you are ready, I'd like to see the flowers. Edit: That's a pretty big plant. Assuming it has or grows a healthy root system, it should put out a nice display of flowers again.