im new at a freshwater aquarium. i FINALLY got my water cycled in my tank, so, of course im excited?

It Depends pet stores like Pet smart will but if they tested your water before you bought fish and it was ok and they test again when bring you any dead fish back and its all ok they should refund or give you a new fish .

Yuo should know the return and gurantee policy of any store before you buy. There is no univeral policy, or law or something requiring they take the fish back. Many local stores have a no reutrn policy as so many people improperly acclimate or house their fish, killing it by their own fault, then trying to blame the store who is not only sad you killed the fish, but upset you try to pin the loss on them.

Your other questions indicate you do not have properly stocked tanks, and are pretty ignorant on proper fish care. The fish store likely knows this. Sometimes they can just outright refuse to sell you anything, as they know you will not care for it properly.

Not always. Can't prove that it was the store's fault and not yours. It's just a they said/you said thing. As far as the fish that died...did you float it in the bag for a while? Or did you just dump it into the tank when you got it home. If you dumped it in right away then you probably shocked it. Fish need time to adjust to the temperature in the tank. Remember that fish can die from stress. It could be something as simple as that.

Yeah, most pet stores do give you your money back when your fish dies in 24 hours. But I am sure not all do. I would just take your business elsewhere from now on. I could have been your fault or their fault. It is hard to know.