When I try to start the IIS I got: The process cannot access the file because it is being used by another process. (Exception from HRESULT: 0x80070020)
Even after reboot it wasn't working
Because this took my quite a while I post this answer hoping this wil losave some one time.
The short described solution
I had to close skype before starting the iis
The details
There are many reasons for this error. mostlikely when port 80 is blocked by another software.
Now Skype uses port 80 and if it is started before iis the port of my default website (80) is blocked.
You can check which application is blocking your port by using netstat
NETSTAT -ano
or any software which shows you who is occupying which port.
btw. in the case of skype it is using another poirt when 80 is used so you won't have any further problem with this