Hi Snookers,
Welcome to our forums.
Please review the general guidelines on how to ask for help, and provide us some information about your setup.
You said the webcam worked in the past, so maybe the best approach would be following back the road of modifications until we find the working configuration. Can you share what and where did you modify? Also distribution information, as well as hardware could be useful.
If there are some error logs/messages, those could too provide us some additional information to help you.