I think you need to update the Graphics driver first from the manufacture website before you open Lightroom.
If that doesn't help, please provide the crash log.
How to find crash log in Windows, refer: Photoshop Elements Editor Help | How to Find Crash Logs on Windows
Still trying after 2 days!
Tried to update Graphics driver. Windows tells me it is best one.
Crash log shows error. I have pasted a copy to my desktop but cannot copy it to this reply.
What do I do now apart from tearing my hair out?
You need to turn off the Graphics Processor from the Lightroom Preferences.
Open Control Panel >> Go to Device Manager >> Under the Display Adapter look for the Graphics Adapter >> Right Click and disable.
Go to Lightroom Preferences from the Edit menu
Click on Performance tab
Uncheck the Graphics Processor
Open and check if it works fine, then go back to the Device Manager and enable the Graphics Processor.
Let us know if that helps.
Did as you said Mohit and Lightroom worked fine until I went back to Device Manager and enabled the Graphics Program.
Tried it a couple more times with same result. The graphics is Intel (R) HD.
Should I leave it disabled perhaps?
Did you disabled the Graphics processor from the Lightroom preferences after disabling it from the device manager.