Regarding the Earth's motion (and the motion of every other planet),
there suddenly wouldn't be any centripetal force to curve the Earth's
path. So the Earth would sail off in a straight line, in the direction it
was moving at the instant when the sun's gravity disappeared.
Although everything would become very dark, you wouldn't feel
anything different. Even now, as we follow the curved orbit around
the sun, the direction of the Earth's motion only changes by about
one degree per day, so we don't feel it.