If you are connected via a single 3.5mm port then that may well be your problem. It could either be output only, so a mic would never work, or it is a not so great input/output one (which is really common) and it can cause them not to work.
You can try the following and see if it resolves it...
1. Go to "Control Panel".
2. Click on "Sound".
3. Click the "Recording" tab.
4. Click on the device you are trying to fix.
5. Now click the "Configure" button and then click "Set up Microphone".
6. Once that is complete, click the "Properties" button.
7. When you are done with your changes, in "Properties", click "Apply" and then "OK".
8. Then click "OK", again, on the main "Sound window".
Should this not fix the problem, you may want to consider getting a 3.5mm to USB adapter (they are pretty cheap) and connect through a USB port instead. This would avoid the problem.