  We present a unified theory of inflation, neutrino mass, baryogenesis and
dark matter where global lepton number symmetry and its breaking play a crucial
role. The basic idea is to use a lepton number carrying complex scalar field as
the inflaton as well as the field that implements Affleck-Dine (AD)
leptogenesis. Dark matter is the massive majoron which is a pseudo-Goldstone
boson, resulting from the spontaneous breaking of lepton number symmetry
supplemented by explicit lepton number violation needed to implement AD
leptogenesis. The magnitude of the resulting $n_B/s$ in the model is related to
the mass of the pseudo-Goldstone dark matter, connecting two apparently
disconnected cosmological observations. Inverse seesaw mechanism with lepton
number breaking at low scale is crucial to prevent washout of the lepton
asymmetry during the universe's evolution. The model seems to provide an
economical solution to several puzzles of the standard model of particle
physics and cosmology in one stroke.
