I must admit that it can be a bit daunting when reading through some tutorials, but scroll down to and read from Recompiling the whole repository (all MOF and MFL files) and lower down looks like a quicker way to do it by Rebuilding the whole WMI repository from scratch.
However, as the article mentions about resetting permissions, then perhaps you should run the Windows Repair program first with default settings (not sure off the top of my head if any additional settings would need checking for WMI problems) and then see what error messages you get.
Before running any major program that will be making registry changes, I always advise creating an external system image first rather than trusting to any restore points etc.