O/S: Windows 7 ,Home Premium
I have just installed IIS manager Express from Web platform installer and Turned on the IIS7 feature from the Program Feature in control panel.
Q) I was playing with IIS Manager (inetmgr) I was able to view the Welcome page on typing localhost but after adding some sites and deleting them I’m unable to see any site hosted on IIS and even can’t see Welcome page of IIS
Note: I was assuming IIS switched off ,but its running
Services.msc from start menu > run

Progress:
After trying Update2 from “Andrei Drynov” here is the sanpshot

Is there page iistart.html in C:\inetpub\wwwroot?
Is the default web site there and running?
UPDATE:
You can you can uninstall and then install again IIS components like Default document, if you really want that welcome page:
UPDATE 2:
I was able to reproduce your issue by creating another web site with site1.com as a host name in Site Binding and removing the default web site. Remove the host name there and you will be able to open the welcome page again: