Lightroom won't open

​@DBTH123 

Do you get an error message?

Which version of Lightroom do you’ve installed?

What has been changed on your system before the error occured?

In a first step you should  try to reset the Lightroom preferences.

https://www.lightroomqueen.com/how-do-i-reset-lightrooms-preferences/

It's recommended to backup your preferences before you reset the preferences to the default settings:

https://helpx.adobe.com/lightroom-classic/kb/preference-file-and-other-file-locations.html

Another issue can be a faulty catalog. Hold the Ctrl-Key while starting LrC. This opens a catalog selection dialog.  

First select the appropriate recent catalog and let it check it – note the checkmark "Test integrity of this catalog" to check its integrity. If that doesn't help, try to create a new one and see if this catalog works.

If yes, you could then try to import your current catalog into the new one. Choose 'File - Import from Another Catalog' and then select your old catalog for import. In the import dialog choose all photos to import, but DON'T MOVE them. This will create an exact copy of your old catalog, but usually without the corruption.

Another alternative is to try to restore the catalog from a recent backup -> Disaster strikes - a corrupted catalog! | The Lightroom Queen