Lack of inspiration is insidious, allowing mediocrity to sneak up like the proverbial thief in the night, robbing us of our very essence and spirit. What's the way out?
Start by setting a goal. (A vision or purpose may be too challenging when you're in an uninspired place.) It needs to be short-term, realistic, measurable (so you know when you've achieved it), time-based and, most importantly, must bring about one change that you want in your life. One thing, no matter what it is, that will mean something to you and improve the quality of your life somehow. Tidying that desk/garage/study; having a make-over (or even just tidying yourself up somehow); finding one way to make yourself more efficient or productive; choosing (or resuming) a hobby; going for a walk or a jog; starting a diary; and so many more possibilities....
Then do it. No excuses, no fuss: like Nike, just do it. The next step is to acknowledge yourself for what you achieved. Feel your grateful for the change in your life and see the value that you brought (and can keep bringing to) your life.
When you're done, try another one. And another, and another...until you break the inertia and get going again. The more successes you have, the more you will reunite yourself with your inspired self and start getting truly purposeful.