If you can hear others, but cannot be heard, and you have confirmed your TeamSpeak is set up properly, and the mic is plugged in, try the following:

Open your volume control:

Either double click the speaker icon in your system tray, or click Start>Settings>Control Panel>Sounds and Audio Devices. Under Device Volume, click Advanced:

The Volume Control bar will look about like this:

At the top left, click Options>Properties

The Properties window will open. Click the Recording radio button. Click OK.

Your Volume Control panel will convert to the Recording Control panel:

At the bottom there is a ‘Select’ check box for each input device your machine has. One or none will be selected. If it is not already checked, check the Microphone ‘Select’ box. Then click ‘Advanced’.

If not already selected, check the 1 MIC Boost checkbox. Click Close.

Click Options>Properties again, and return to the Volume Control panel:

Uncheck the Mute check box if it is checked.

You should be audible to others on Teamspeak now.