Lightroom Classic non funziona

What has been changed on you system before the error occur?

Do you get an error message? If yes, please post the exact message or an screenshot.

Please try is to switch off the GPU support from the Lightroom preferences and check if that helps to fix the issue.

Go to Lightroom > Preferences > Performance tab > Uncheck "Use Graphics Processor" > Restart Lightroom.

https://helpx.adobe.com/lightroom-classic/kb/troubleshoot-gpu.html

If Lightroom doesn't start correctly the please see "Solution 2" in the document behind the link below.

Troubleshoot GPU issues | Lightroom Classic (adobe.com)

Another step is to 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

If this doesn't help try to create a new Admin account and check if LR runs within this account. 

Adobe troubleshooting: Creating an admin account in Windows

If the steps above doesn't help I would suggest a complete and clean reinstallation.

Please follow the steps below:

• backup all personal data, like templates, presets, catalog(s) etc.
• uninstall everything cc including preferences,  https://helpx.adobe.com/creative-cloud/help/uninstall-remove-app.html
• then uninstall the cc desktop app,  https://helpx.adobe.com/creative-cloud/help/uninstall-creative-cloud-desktop-app.html
• clean your computer of cc files per http://www.adobe.com/support/contact/cscleanertool.html
• restart your computer (don't skip this)
• reinstall the cc desktop app,  https://www.adobe.com/creativecloud/desktop-app.html
• use the desktop app to install your cc programs/trials
• restore your personal data.

If you're unable to install the cc desktop app at this stage, use an administrator account (solution 4 here,  https://helpx.adobe.com/creative-cloud/kb/creative-cloud-missing-damaged.html)

You may be experiencing the issue described in the thread I've linked below. Please, try the steps set out in the pinned reply just below the first post. Let us know if it helps or not.

https://community.adobe.com/t5/lightroom-classic-bugs/p-lrc-12-2-1-fails-to-start-launch-or-is-extremely-slow-launching/idi-p/13673512

Please Consider including the following in your question:

• Adobe product and version number
• Operating system and version number
• The full text of any error message (s)
• What you were doing when the problem occurred
• Screenshots of the problem
• Computer hardware, such as CPU; GPU; the amount of RAM; etc
• Provide also a copy of your 'System Info'. This can be get from the LrC Help > System Info menu item. There's a copy button in the System Info dialog. Press this button and paste the info into your next forum post.

Thanks. The above info will help to solve your problem.