When you hold down Ctrl, Alt + Shift on launching Lightroom, you are prompted to select a catalog or Create a new one.
Once you create a New one, the Application will launch. (This will not resolve the issue you have with the Catalog)
At least you will be able to Launch and use the Application again.
For Suggestions on repairing a Corrupted Catalog have a look at the Blog of the Lightroom Queen:
Hope this will help you!