It probably happens to mostly all of us (except a few freaks of nature, I guess ;p)
As somebody touched on earlier, I like to really shake things up, if I can. One of these creative ruts is what got me into actual 'metal' in the first place, and another is what got me to branch out and like other things than metal. Another later one got me interested in production/recording, and yet another got me interested in synthesizers and sampling. I guess in the end, these periods of feeling like a goober have been a major force in making me what I am now.
Find something that's interesting to you, even if you don't necessarily like it much, and try to dive into it. If you fail, find something else. I got into recording/production by fiddling around with software and forcing myself to try to finish a song. I got into synthesis by downloading a few free soft-synths and saying "I'm not going to quit this until I at least vaguely understand what all these knobs do." Funny enough, learning these somewhat tangential things helped me out as an overall musician probably more than slamming away at scales and modes on the axe.
I've even at times forced myself to do stuff that never actually turned out very good, but at least forced myself out of a rut: things like saying "I'm going to write/record X in 24 hours" or something like that. Maybe "I'm going to write a pop song" or "I'm going to write an electronica track" or something.. anything that might stretch you a bit. I've heard stories of people purposefully snapping strings or tying them off to make themselves view the fretboard in a new light. I actually personally used to force myself to spend days doing one particular thing almost exclusively: when I noticed that my Alt-Picking was way more developed than my legato, I spent a week or two where I didn't even let myself pick up a pick. Trust me, it helps ;P
If none of this works, maybe take a few days off, watch a bunch of TV, play some games, read a book, etc... then come back when you have a few hours, abuse the substance of your choice (I tend to just have a few beers, but I've got friends that go a bit more overboard here) and jam to your favorite music really loudly. Hopefully even if you don't learn anything, it'll really reinforce that you love music and WHY you love it, and you won't have to try very hard to feel the 'spark' again.
It really does, even if for short times, happen to most/all of us. The trick is to not get to upset about it, and either force your way through it, or trick yourself into forgetting about it and learning something new
