Laptop insight

Hello. My mother has a Compaq Presario laptop and her harddrive recently crashed. She only used it for three months (Dec. to March) for two years and the rest of the time it was turned off. During the three months (six total) that it was in use, she kept it running by utilizing the standby feature. Incidentally, the standby feature was the first thing to become problematic – the computer no longer recognized it, and finally the entire computer crashed. Any advice as to why this happened andhow she can prevent it from happening again? Thanks in advance.