iTunes creates an empty library file in Windows
Some file scanning software products that are not made by Apple, such as the Sony VAIO Entertainment Platform, may damage your iTunes library. If the library becomes damaged, iTunes may create a new, empty library.
Although the library appears empty, the media files should still be in their original locations. By default, this would be the iTunes Media folder. For more information on iTunes files and folders, please refer to the following articles: What are the iTunes library files? and Where are my iTunes files located?.
Sony VAIO computers
You should be able to resolve this issue by downloading the Sony's VAIO Entertainment Platform update (version 3.4 or higher). Check the Sony website to see if this update is available for your computer model.
Other computer brands
In Windows, some background processes can cause issues for other programs and processes. These conflicts can prevent applications such as iTunes and QuickTime Player from working correctly, opening, or even installing. You might be able to resolve these conflicts by disabling some items using the System Configuration Utility (MSCONFIG) in Windows.
For more information on using the System Configuration Utility, please choose the appropriate article below: