Whirring turned into a loud clunk

1996 Ford Ranger, Automatic, 61,000 miles - Started with whirring noise coming from drivers front. Promptly drove it back home and let it sit for 5 days. Upon restarting, whirring noise is gone, but when I reversed it out of the driveway a loud clunk was heard and I could feel it through the floor board. Seems to drive ok otherwise tending to make more clunking noise upon turning the wheel. Had it in 4 wheel drive a couple of weeks ago but back to 2 wheel now. Could this be a problem? I'm scared to drive it since I don't know whats wrong and being a girl I don't want to be "taken for a ride" when I go for repairs.