What happens when you try? Does it work in Safe Mode? Can you find
info that may be related to the problem in the Control Panel >
Administrative Tools > Event Viewer?
What changed between the time things worked and the time they didn't?
What is the virus/malware status of the computer? This could be caused
by quite a few things and since we don't know anything about your
computer all I can do is suggest you start your troubleshooting by
looking for malware since that is a common reason for this sort of
problem.
It is completely possible to run virus/malware scans without using
Explorer (the Windows graphical user interface) but it requires some
skill and comfort with the commandline. If this isn't you, then take
the machine to a professional computer repair shop (not your local
version of BigStoreUSA). Otherwise, here is a procedure to go through
systematically:
