I don't know whether your problem remains for you but I remembered that someone asked for help for the same problem before. Here it is:
Emotisounds
But before reading it, I'll ask you some questions.
Do you hear winks' sounds? (To check it, select Tools>Winks in a conversation window's menubar and when Winks window is opened, select a wink and press on Preview button. Did you hear the sound integrated into that wink?)
Do you hear Windows events' sounds, for example while you are logging in or out Windows? (You can check those sounds manually, either by right clicking on Speaker symbol at systray (where the computer's clock is shown) and then select "Set Sound Features" or by going Control Panel>Audio, Speech and Music Devices>Sound Effects and Sound Devices. When you open that window, switch to "Sound Effects" tab and select an event among "Program events" there and try to play it, did you hear the sound?)
If you cannot hear those sounds as well, I recommend once more to check the connections of your speakers. Make sure every speaker cable is connected to the proper slot on your sound card. This is highly important.
If they are correct, try updating your sound driver. (You must click on Hardware tab on "Sound Effects and Sound Devices Features" window and select your sound device in the devices list. Press on Features button, it will open a new window. In that new window, press on Driver tab and press on "Update Driver" button. If this doesn't solve your problem, you can give a try to
aphrodite's complex solution.