What is this w3wp.exe error while browsing the website?

My asp.net website hosted on window server 2008 has suddenly stoped working. When i browse the website and exception is show on the server saying something about w3wp.exe error. Even if i run the website in visual studio on server it still not working. I have tried a lot to fix it but could not find a solution.

Here is the screen shot of the error on event viewer:

Can anyone here help me fix it?

Thanks