Sometimes, Visual Studio fails and you can’t do anything. You can repair or reinstall but in this case it’s not works.
PROBLEM : You can’t see any Emulators on Visual Studio :
and when you try to compile it throws 0x80070002 (File not found exception) :
SOLUTION :
So there are missing files, I catch them with ProcMon and by using MultiTargetingConnectivity API (this is THE api which throws 0x80070002) They are here in this location C:\Users\[Your User]\AppData\Local\Microsoft\Phone Tools\CoreCon\11.0
They are :
– Microsoft.ServiceCategories.xsl,
– Microsoft.VisualStudio.ServiceCategories.xsl
– Microsoft.XDE.ServiceCategories.xsl
– Microsoft.TypeMaps.xsl
It can be difficult to retreive these files (I repaired reinstall SDK 8 with no luck, trying to remove 11.0 directory and reinstall etc) so as I’m a nice guy, you could find the directory 11.0 zipped here : Download the full directory 11.0, extract here and copy/paste the missing file in your directory.
Have a nice coding day 
Stephane