Hello,i have acer netbook with vista basic. webcam was fine.I upgraded it to windows 7 (webcam still works)but it was too heavy. so I downgraded it to xp but now the webcam won't work. Tried to get it back to vista basic but webcam still didn't work. Is it possible that unless you upgrade it back to windows 7, the webcam won't work at all?please help me.
If you did a complete reinstall, what is most likely is that you didn't reinstall the proper driver for the webcam.
You might try checking the device manager and see if there are any devices flagged with yellow warning signs. If yes, then you want to try to find the device/model name so that you can download the appropriate drivers.
Webcams were not at all standard when XP came out, and were just becoming mainstream with Vista, so it's likely that neither (especially Vista Basic) have the appropriate drivers, while Windows 7 should have them by default.