If there is new fad that decreases the demand of a good, how could you amend the issue only involving the price?

The answer to this depends on what you mean by “amend the issue.”  If you are asking what you could do to the price of the good to raise its demand back to previous levels, the answer is “nothing.”  If you are asking what you could do to raise the quantity demanded back to previous levels, the answer is “lower the price.”

These answers are based on the difference between a change in demand and...

The answer to this depends on what you mean by “amend the issue.”  If you are asking what you could do to the price of the good to raise its demand back to previous levels, the answer is “nothing.”  If you are asking what you could do to raise the quantity demanded back to previous levels, the answer is “lower the price.”

These answers are based on the difference between a change in demand and a change in quantity demanded.  Demand can be defined as the amount of a good that people are willing and able to buy at a given price.  In the case you pose here, a fad arose that made your product less popular. People are now willing to buy fewer of your product at a given price.  You cannot change this by changing the price because we specified that demand is the amount that people can and will buy at a given (cannot be changed) price.  The quantity demanded, by contrast, does change when the price changes. The law of demand tells us that, ceteris paribus, people will buy more of a thing as its price drops and less of it when its price rises.  What this means is that you can get people to buy more of your product if you lower the price. This will not raise demand, but it will raise the quantity demanded.

Thus, we can say that there is no way that you can change demand by changing your price.  However, you can increase the quantity demanded.  Which of these would meet your definition of “amend the issue?”