Accidentally deleted /Library/Developer files
I accidentally deleted my /Library/Developer files while trying to delete the Derived Data. Now, My Xcode 9 has stopped working and is crashing everytime I open it. I have a extremely important project pending. I am using macOS Sierra.
Open Terminal from Application -> Utility -> Terminal Type in the following.
xcode-select --install
This should install Mac Osx commandline tools and also create the /Library/Developer Files