I cant open my web cam screen said webcam not found

Sounds like the drivers for the webcam may need to be reinstalled. However, it is possible that the webcam is faulty. If it is a built in cam, then you may need to send it into Acer to be repaired/replaced. Remember if you do send it in, they will re-image the hard drive, so make sure you have a good backup of all of your important information.