That error can often occur if you don't have proper drivers for your hardware, in this case your webcam. Sometimes this can arise after updating Windows, and would explain why you're webcam isn't working.
Go to the manufacturer's website, download and reinstall the lastest drivers for your OS and hardware. Let me know if that does the trick.
i am sorry it's only now that i came back for this. i brought my laptop now to te service center since i don't know what to do with it. yeah, it might be the driver because everitime i turn on the laptop, it says THE DRIVER WAS NOT INSTALLED SUCCESSFULLY, thank you.