Which country are you in?

The hot/neutral is easy to fix - just turn the power off, unscrew the
socket plate from the wall, swap the hot and neutral connections over
and put it all back.

The open ground is not so easy. You could check for loose connections
on the ground wire or replace the cable from the socket back to the
switch board.

wrote:
I bought one of those 3 neon bulb testers to check the wiring of a new
house some friends of mine bought. In one room, all of the outlets read
Open Ground. But there is one outlet in the room which will read
Hot/Neutral Reverse when it has an appliance (with a 3 prong plug) in
it. Otherwise it also reads Open Ground. It will also read Hot/Neutral
reverse when the GFCI test button is depressed. Any ideas?