Ok so my Eleca Les Paul has a thin crack on the fret board going from the 12th fret to the 15th with this affect playabillity.

Also theres alot of black gunk around the frets how do I remove this?
Pics of the crack? And eventually it'll spread and get bigger, and it WILL effect yer playability. If it gets untreated.

And I get rid of the black gunk by scraping it off with a pick, but that's not the best soloution. Just clean it off by using some elbow grease.
Cam Sampbell's my hero
Send it off to a Luthier or a good guitar store. You could make the crack even wider if you fiddle around with it. As for the black gunk, try a thin pick or the tip of a sharp knife. Be careful not to cut your guitar though.