If you encounter difficulties with this please make a new forum post or bug report with a descriptive title and enough information like steps to reproduce the issue or logs so we have something to work with. Please only one issue per forum thread. Otherwise user with the same issue may not be able to find any solution and for people trying to help multiple problems at once are to hard to follow. Just good manners.
Be aware we really, really, really, will need to know exactly, exactly, what you have done to your computer before the issue occurred. This is essential information. If you have customized your system we may need to know exactly, exactly, what you have done. Again essential information.