Why QuickBooks Won’t Open is explained here. Every time you encounter a "QuickBooks has stopped working" or "QuickBooks is not opening" problem, one of the following is usually to blame:
The files that run Windows are broken.
Your hard drive contains corrupt or damaged sectors.
The name of the QuickBooks company file is longer than the permitted number of characters.
On Windows, QuickBooks is not properly installed.
The QBWUSER.INI file, which is used to store initialization data, is either not present or destroyed on Windows.