I got fleas in my house. it's the second time. help anybody? where are they come from?

Take a pan of warm soapy water and put it in the middle of the room with the infestation. Put a lamp light on, over the water to keep it warm. Do this in such a way that there is no possibility of the light falling over into the pan of water. Then turn off all the lights and leave the room. If you maintain this warm soapy water you will kill all the adult fleas. Then, you need to see about vacuuming up fleas (use moth in your vac bag). Last, the eggs, will hatch in a few days. There are treatments, there are chemicals which you can treat the affected area and the cat, but personally, I'd maintain vigilance until they are all dead. Their cycle runs about a week I think, but you might want to check that. Good luck.