PC not recognizing a digital camera, why?

Some time PC stop recognizing the external device it may be all or some specific one. There may be different reasons behind the stop recognizing the external device. It may be happening due to some virus or it may be happening due to some of your OS files get corrupted or it may be happening due to the software that you have installed recently. So for the proper checking of the reason behind this. First of all check the status of your antivirus. If it is updated and working very well than try to remember the software that you have recently installed. After that uninstall that software and try to rerun that. If your PC resume its services than it is ok. If still not than it is happening due to your OS get corrupted, For that you have to reinstall that. After that Try to install your camera driver again and check if it is working if yes than now your problem have removed permanently.