To restart PHP on IIS, you actually need to restart IIS:
Click Start, click Run, type iisreset, and then click OK.
If iisreset command is not recognized, then click win and search
"Turn windows features on or off" and tick the checkbox
"Internet Information Service" and click ok and after completion try above
process again.
Win + R type:iisreset
Or, more verbose: iisreset inside a powershell
opened as administrator - or even inside a Cygwin shell.