Upon trying to edit our web.config file on our SharePoint 2010 Enterprise server via "wss\VirtualDirectories\80", Visual Studio started up to load the file for editing and then threw an error, something like an "unknown exception", and then refused to load the config file. Subsequently, the \80 folder shows that the web.config file no longer exists there! It's not in the recycle bin and is not found in any of the sub-folders under \80. Obviously this breaks the entire SharePoint farm connection. Is there any way to recover the web.config file?
First thing, You should always keep a backup of web.config and shouldn't touch it unless you know what you are doing.
If your web application isn't customized then just create another web application in CA which will create a new web in IIS too a and virtual directory for it. You can copy newly created Web application's web.config to create a web.config for your old web application. It happened to me so many times.
Web.Config is just xml document with elements that you can use for web application's configuration for example if you want to see full trace errors, so building a new one from scratch shouldn't be rocket science until you know what exactly you want.
This file also contains safe controls entries which you will need to add if there's any control that needs to in it. I have seen IIS manager making backup copies of web.config on my development server and web application's virtual directory if you could find it.