hello I have Proxmox installed I have several services that are running but today it happened to me that I installed a certificate and the web interface does not want to open
99,9% of the people here will have proxmox installed, so telling us won't really help, nor get your topic looked at by most.
Better to have a title like "web-interface does not open after installing certificate"
To help a little though:
Can you still reach your server through either SSH or by logging into the console/monitor of your PC/Server?
if so, what is the output of the command systemctl status pveproxy