Open the Activity Monitor ( You can search it top right hand side corner in Spot light).
Once its open, look for the Lightroom Process running
Select it and Click on Force Quit.
Then try to re-launch the Lightroom.
If the above steps didn't worked, please restart the machine and then try to launch Lightroom.
Let us know if that helps.
ok did that it just trys to open then disappears
Go to /Library/Application Support/Adobe.
Look for two folder SLCache & SLStore.
Trash both the folder
Try re-launch the Lightroom.
If the above steps not helpful, simply go to Application folder and uninstall/Trash the Lightroom
Restart the Machine
Thanks ! working again after re install,