Mac or windows? What version?
What exact version NUMBER of lightroom (x.y.z) ?
Are you getting any error messages? If so, what is the exact wording?
Step by step, in great detail, you need to describe what "not working" means.
The only version number I'm aware of is 6. It is the version just released
There are no error messages.
"Not working", as I described it, means it will not even open. Therefore,
there is no way to use it.