I don't know what is the cause of this problem. I actually saw that the texify.log file is empty. Could that be the problem?
Sorry, but "C:\Program Files\MiKTeX 2.9\miktex\bin\x64\texify.exe" did not succeed.
The log file hopefully contains the information to get MiKTeX going again:
You may want to visit the MiKTeX project page, if you need help.