The year is 1848. You are a member of one of the following classes: middle class, working class, or aristocrasy.You live in one of the following countries: England, France, or Austria.Discuss how the events from 1789 (the French Revolution) until 1848 (the end of the Age of Metternich) have affected you and your family.

This question gives you a lot of options. Given that you can choose to be in one of three classes from one of three countries, there are in fact nine different scenarios you could write about here. As such, it is best to let yourself be guided by the events and ideas defined in the question: the French Revolution and the Age of Metternich.
I assume you have been studying this in class. Do you have a preference for, or greater confidence about, the history of any one of these nations? If so, I would be inclined to choose that one. Personally, I think the most difficult of the countries to choose would be England because the question focuses upon political change in mainland Europe. While there were certainly significant changes to British society driven by the French Revolution, the subsequent unease about the rights of the monarchy, and the rigidity of the class system—not to mention the religious unease which followed—if you are struggling with this question, it might be better to focus on France, where the effects of the Revolution were much more clearly felt.
In terms of choosing an area where the effects would have been most extreme, it might be easier to focus on either the working or aristocratic class. The French Revolution saw a surge in the middle class in France, as social mobility became increasingly possible and the merchant class profited. However, the position of a person who was an aristocrat before the Revolution, provided that he or she survived the ordeal, would have been radically different after the execution of the King and Queen, and life over the next sixty years would have been a continuous period of adjustment. The same would be true for a person who had known absolute monarchy at the time of his or her birth into poverty but was now experiencing the radical overhaul of society.
Importantly, the time period defined in the question is bookended by two revolutions: the first French Revolution, and the February Revolution of 1848. A person who was a young adult in 1789 would have experienced the following:
1. Ten years of fighting and political turmoil, culminating in the overthrow of the French monarchy (to 1799), resulting in a secular society which had thrown out its Catholic roots and driven significant social change.
2. The expansion of the French Empire under Napoleon and the Napoleonic wars, with Napoleon as Emperor of France (1804–1815).
3. The restoration of the monarchy in 1814 but under different constraints to the original French monarchy. This monarchy was constitutional only—during this period, industrialization began in earnest in France and an economic recovery from the wars began.
4. The overthrow of Charles X by Louis Philippe in 1830, which saw a massive rise in the importance and political clout of the wealthy upper-middle class, plus colonial expansion for the French alongside many other European states.
5. Numerous revolts against the July monarchy, which ultimately resulted in the 1848 revolution. This created the Second Republic, which was driven by working-class opposition to the increasingly conservative monarchy.
That is an unprecedented amount of change in a very short period of time. It is part of what is often called France's long nineteenth century. As a member of a working-class family, how would all of these events and social changes have affected your life? Under the first monarchy, you would have effectively been a serf, probably an agricultural worker, undoubtedly a Roman Catholic, and at the bottom of the social pecking order with no political power. Over this period, you might find yourself fighting for Napoleon, becoming a factory worker and moving to a big city for work as industrialization picked up, or becoming politicized and joining a revolution (or several).
If you had been born into an aristocratic family, meanwhile, your circumstances would also have undergone radical change over this period. You might have seen members of your family executed, been forced to go into hiding, and watched society become increasingly secular. Society shifted from viewing the king as being ordained by God to a point where the power of the working classes could end monarchies (more than once). That is a busy life for anyone.
I hope this gives you a place to start!