VS2015 open failed

In the course before using VS2015 can open .Net project, the result of a sudden you can not use. I can not understand, then to find a way to try holding the mentality of the results will be successful.

 Solution

first step:

 Start -> All Programs -> Microsoft Visual Studio 2015 -> VisualStudio Tools -> VS2012 developer command prompt (run as administrator mode)

Step two:

Run devenv / Safemode 

third step:

Reopen vs to get!