There are number of posts on this and I have tried many a things by now. But to no avail. Myself a Winforms Developer basically, started working on this Web stuff few days b
In my case I checked event logs and found error was Cannot read configuration file ' trying to read configuration data from file '\\?\', line number '0'. The data field contains the error code.
The error code was 2307.
I deleted all files in C:\inetpub\temp\appPools and restarted the iis. It fixed the issue.