You the drivers for your hardware, I'm guessing this may be a laptop with a built in mic, so go to the makers website and download from there.
You should always provide more information about your system, like make and model when asking for help, so that we know what we are dealing with.
It seems the microphone is not configured properly on your computer. You may try resolving most microphone/line-in problems by following steps, in order, to test, check hardware and connections, update audio drivers, and configure Windows sound settings. If you follow these steps in proper order, you will fix the problem or you will find that the audio software being used needs to be configured or updated.
Step 1: Testing for an audio signal
1. Click Start, and then Control Panel.
2. Click Hardware and Sounds, and then click Managing audio devices...
3. Click the Recording tab.
4. To test the microphone, speak into it. To test line-in, send a signal to the line-in port from the source audio device (press play from the audio player). Look at the gray bars next to the device name on the recording tab:
* If the gray bars next to the device name change to green, this device is active and an audio signal is being passed through the microphone or line-in port. This step shows that problem is related to sound settings in the software that uses the microphone. If you have not already done so, set the selected device to default and adjust the levels. Once the device is set to default and the levels are set, use and adjust the sound recording or voice carrying software.
* If the gray bars remain gray and inactive, the device is not recognizing a signal. Leave the recording tab open and go to the next step.
Step 3: Check volume levels and mute
The speaker volume for the microphone and line-in may be muted or turned down. Use the following steps to check the speaker volume levels for line-in and microphone.
1. Click Start, and then click Control Panel.
2. Click Hardware and Sound.
3. Click Sound.
4. Select Speakers, and then click Properties.
5. Click the Levels tab.
6. Click the Muted button next to Microphone and any other line-in that is muted.
7. Use the slider bar to raise the level for Microphone and each line-in to at least 75.
8. Click OK.
Step 4: Update the audio drivers
You may find that a front microphone port does not work, a recording device is missing from the recording tab, a microphone is not recognized when it is plugged in, or other problem. There may be updated audio drivers that can fix these types of issues. Use the following steps to make sure audio drivers are up to date.
1. Connect to the Internet.
2. Click Start, and enter device manager in the Start search field.
3. Click the plus sign, next to Sound, video and game controllers.
4. Right-click the name of the sound hardware and select Update Driver Software....
5. Click Search automatically for updated driver software and wait for Windows to update the driver software.
6. Windows checks a remote Web site to see if updated driver software is available.
* If an update is available, let Windows install the update.
* If an update is not available, skip to the next step.
7. Once the update is installed successfully, test the microphone or line-in as was done in step 1. If the problem persists, go to the next step.
Step 5: Configuring Windows recording settings
By default, Windows Vista automatically enables microphones and line-in ports. Use the following steps to set the microphone/line-in port to be the default port and to configure the recording levels.
1. If the Recording tab in the sound window is not selected, open the Sound window and click the Recording Tab and make sure that the status is set as below.
1 - Microphone port - working and set as default
2 - Line In - working
3 - Digital In (S/PDIF port) - working
4 - Stereo Mix (Software mixer) - Disabled
1. If multiple microphones or line-in ports are available, select the port that you want to use. Click Set Default to make this device the default audio input device.
2. If the device you want to use contains a small circle with an arrow pointing down, the device is disabled. To enable the device, right-click the device name and select Enable.
3. With the device selected, click Properties, and then click the Levels tab.
4. Adjust the slider until to 75% of its range.
5. If Mute is on, click the mute button to unmute the device. The mute button should show as a blue speaker without any red circle.
6. If Microphone Boost is available, adjust to +20.0 dB.
7. Click OK to make the changes.
8. Test the microphone as was done in step 1 to determine if Windows is able to detect a signal for the microphone or line-in being used. If you have performed all the steps and the microphone or source device still does not work, the audio ports or sound hardware on the computer may be bad.