Webcam of new Medion Akoya P7618 does't work. Doesn't appear in devicemanager.

Goto Medion website-support and download latest drivers. Install these.

It could be that you need up to date sound drivers. You can download from
http://johnsondrivers.com/download-driver/MEDION/AKOYA-S4213-MD-98064
If that fails, take it back to your retailer or get in touch with Medion

You upgraded to Win 7? From what? Internal webcam?

Reinstall webcam driver.

Try Manycam and see if it works with Unbuntu. Go to www.google.com and in the search box type: "download cnet" (without the quotes) and go to their site. Look down on the left and you will see a gray box that says find software. Type in: "Manycam" (without the quotes) and go download and install it. It's absolutely free, no trial period and it comes with application and I think driver. Give it a try. Be sure not to accept any buggy stuff that it will ask you during the install.

Install an webcam viewer software and install it.

I don't know where are you located but this company could be a great start where you can find your inverter:
http://www.laptop-lcd-screen.co.uk/laptopparts/MEDION-AKOYA-E5312-15.4-LAPTOP-SCREEN_7500.asp

for how long have had the system?every new system comes with a warranty...so i suggest,with your proof of purchase in hand take it back.

go to www.lavalys.com download everest ultimate go under periferal/ windows periferal verify if your webcam is listed dont forget to check under unknown periferal if your cam not is listed you are screwed if its lister you will have a full description or your webcam brand and model search trough google or www.driverguide.com for your new driver install it and everything should be fine if you have other question dont be shy

I have just bought the same Laptop, when windows Vista is started the webcam doesn't work. By pressing the keys FN + F9 the webcam will be activated (you have to do this every time you start your laptop)