Chances are the path "%systemroot%\System32\WindowsPowerShell\v1.0\" was removed from the PATH system environment variable. Removing the path to powershell.exe from the PATH variable made it impossible for you to refer to powershell.exe from any random command line location without fully qualifying it.

As a side note the explicit path you decided to prefix your command with, "C:\Windows\SysWOW64\WindowsPowerShell\v1.0\", is the path to the 32-bit version of powershell.exe on 64-bit OS'es. Prior to the upgrade it is likely you were executing your script using the 64-bit version. Chances are it is not making a difference since you said the script is working but I thought it was worth pointing out.