After upgrading from windows 8.0 to 8.1 office 2013 programs will not load and no error message, goggled this NG, went to Microsoft website NG.
Tried the suggestion of Quick and Long repair of Office through Control Panel, Programs.
Windows 8 had all updates prior to free upgrade to 8.1, since upgrade all updates have been install, computer has been restarted several times.
I use Iolo's System Mechanic 12.5 as a tune-up program, it works great by the way.