This is a bug I found in many versions of Xilinx Vivado package and I actually now struggling with it in 2017.2 version. I don’t check out newer versions so it maybe already been solved, idk! Anyway, in my version on the Linux platform, if you open the SDK normally and then for whatever reason kill the machine or the program you cannot open the SDK again whatsoever. As I said I’m running Vivado on Arch Linux 2016.10 version so again this maybe not happen on Windows hosts.
There may be a lot of workaround for this, but this works for me more or less.
<Vivado Project>/<proj name>.sdk/.metadata/.plugins/org.eclipse.core.resources