Apple mobile device support wasn't installed om your computer

For general advice see Troubleshooting issues with iTunes for Windows updates.

The steps in the second box are a guide to removing everything related to iTunes and then rebuilding it which is often a good starting point unless the symptoms indicate a more specific approach. Right-click on the setup file and run the installer as administrator. It may also help to pre-install the Microsoft Visual C++ 2005 Redistributable. In some cases you may also need to temporarily disable any anti-virus software.

Review the other boxes and the list of support documents further down the page in case one of them applies.

The further information area has direct links to the current and recent builds in case you have problems downloading, or want to revert to an older version if the current one won't work properly for you at the moment.

Your library and device backups should be unaffected by these steps but there are links to backup and recovery advice should it be needed.

tt2

You could try creating a fresh user profile and see if you can install iTunes in that, otherwise see this post on generating an installer log file and see if anything suggests itself from that Re: Re: Unable to install AMDS Apple Mobile Device Service.

tt2

Is this computer on a corporate network where it could be subject to any group policies that might act as a malware defense? On my network for example executable files cannot be run from the temp folders, which is the kind of trick that some legitimate installers also use. Did you install the C++ component? Did you try explicitly running the main installer as the administrator? Have you tried running the Microsoft Fixit tool yet?

tt2

Windows Defender is unlikely to cause an issue. The pre-release build of Windows might do. I'd try installing iTunes 12.5.5.5 from the installers section of the user tip.

tt2

Do you have any anti-virus software? What was the last version of iTunes that worked for you?

tt2