Your website is working before installing the new theme?
Could you access admin dashboard after installing the theme?
Please run the below command:
php bin/magento setup:upgrade php bin/magento setup:static-content:deploy -f php bin/magento cache:flush sudo chmod -R 0777 var/ pub/ generated/
Hope this can help you! Let me know if you need further assistance.
If issue solved, Click Kudos & Accept as Solution.
Did you home page stop working after you started installing a new theme?
Were you able to successfully load it after the installation?