Use the noun disuse to describe a condition of not being used. After years of disuse, you won't be surprised when your dad's motorcycle doesn't start.
The word disuse implies at least a bit of neglect, and it can also mean that something has become obsolete or old-fashioned: "Typewriters fell into disuse after personal computers became available." You'll often find the word used in the graceful phrase "fall into disuse." The word comes from a Latin root, dis, which means "lack of," added to the word use, and it's been around since about 1400.