Localhost - Xampp server

After I installed comodo firewall, I can not enter the localhost root on my browser.
Does anyone know how to solve this problem

Doesn’t it trigger any alerts from CPF when you start Apache?

When I startet Apache the first time (from xampp control panel) CPF asked me to allow or deny it. I checker ‘remember …’, clicked ‘allow’ and that it was.

Check the log to see what gets blocked when Apache is running and you try to access it.
Check if Apache is allowed and if loopback connections are allowed.