If your Medion Sound Card is giving you any kind of troubles, the first thing you have to do is diagnose the problem. Computer hardware is never simple. There are multiple ways, some simple and some complex, that a sound card could give you problems. Outside of the card dying, though, all of the ways are fixable.
Make sure your device drivers are up to date. When your Medion Sound Card was first installed in your computer, a small piece of computer software was also installed. This is called a device driver, and it was designed to insure your hardware (the sound card) can coexist with your operating system. If the driver is not the most updated version, this could lead to many problems. Go to the Medion website, find the page for your specific model of sound card and download the latest device driver.
Make sure your Medion Sound Card is plugged in. If you've recently moved your computer, the card could have come out of its socket connected to your motherboard. Open your computer's case and look inside. Your sound card should be firmly pushed down into its PCI slot on your motherboard and locked in with a small clamp.
Make sure your Medion Sound Card isn't physically damaged. If your sound card is damaged, it is going to have to be replaced. You can check this by removing it from your computer and placing it inside a computer you know works and you aren't having problems with. If the sound card works in the new computer, you have a settings problem. If the sound card doesn't work inside the new computer, the card is broken beyond repair.
Make sure your Medion Sound Card settings are correct. Use the "Audio Devices" option in the "Control Panel" to check all the settings associated with the card. Make sure no speakers have been accidentally muted.
Check the device manager. When all else fails, right click on the "My Computer" icon on your desktop, select "Properties," then "Hardware," then click on the "Device Manager" button. This brings up a list of all hardware installed on your computer. The listing for your sound card should have no icon next to it. If it has an icon with a yellow exclamation mark, double click on it and it will tell you what the problem is.