'jquery' is not a valid script name. The name must end in '.js'

My ASP.Net project is working well, when suddenly we had a power failure. When I ran my web app, it is now showing a lot of

Could not load assembly Sanitizer..." then "Could not load "HtmlAgility...

errors. I was able to resolve these previous errors by uninstalling / reinstalling them using Manage Nuget Package Solutions inside Visual Studio 2012.

But now I encountered another error:

'jquery' is not a valid script name. The name must end in '.js'."

I tried to do same thing by re-installing the package but it does not work. What should I do to resolve this? I already have a jquery.js file located on my root\Scripts folder. I also added reference to this file inside my section:

<script src="Scripts/jquery.js"></script>

But still it won't work. Please help.