FH+ is a piece of crap honestly. You're better off downloading the regular FH in the links given above.
Really the only reason your character was in blackness was because the map you were in doesn't exist in FH+. And you can't exactly fix the problem until you download the normal FH anyway (because downloading the Lonely Cave map is apparently difficult...)
Anyways. Download normal FH. If you still want to play FH+ as well after that, you can take your character to Bonfire island with the normal FH and then log back in on FH+.
Hope that clears some things up.