Might have been some invasive antivirus program that deleted it. Can happen shortly after an update.
If you happen to use a third party AV program, consider switching to Windows Defender, which rarely causes trouble. There is no real need for third party AV anymore, Windows Defender is more than good enough for all intents and purposes since several years. Windows Defender gets enabled automatically when you remove third party AV.
If you didn’t keep the installer for a reinstall, you can get one here:
http://www.vorpx.com/request-new-download/