Is Love's Labour's Lost a comedy? Berowne sure doesn't think so. Think about when he says: "These ladies' courtesy / Might well have made our sport a comedy" (5.2.948-949).
On the other hand, the play features confused, incomplete people wandering blindly through the wilderness before finding themselves and each other. Plus, there are all those jokes. And the closing musical number. That seems like comedy, folks.
The play is also a pastoral. The pastoral is an old, old poetic form. (We're talking old—3 B.C., when Theocritus wrote poems praising the life of Sicilian shepherds.)
In Shakespeare, the pastoral often compares a complicated, neurotic court life to a simple rustic one. In the country (or in Love's Labour's Lost), characters can cast off the court's rules and behave more freely and recklessly: they're getting back to nature. In this play, the outdoor setting, the abundance of nature imagery, and the cast of stock characters including a milkmaid, schoolteacher, curate, constable and "rustic" are all signs pointing to pastoral.
Using pastoral conventions, Shakespeare highlights the theme of the irrepressibility of nature... as well as its tendency to make people think about sex, sex, and more sex.