external hard drive problems

[Victor]

i just bought 240gb lacie external harddrive. i transferred a bunch of data (music, movies, porn) onto it and it worked fine for a week.

then, all of a sudden, when i plugged it in, i got an error that it was unreadable. i havent gotten it to work since.

so, my questions are:
1) is my data retrievable.
2) why did this happen and how is it prevenable?