Security, Operating System Re-Image/Reinstallation
Technology Services' internal Security group may ask a user to reinstall, wipe, or re-image their device's operating system to be totally sure anything malicious is gone. That isn't normally something the Help Desk assists with, but this article contains some helpful resources.
Options for reinstalling macOS can be accessed from the "macOS Utilities" recovery boot. For older devices, this is reached by holding down the Command and R keys while macOS is starting up; on newer devices, simply hold down the power button while it starts.
Apple provides more information about reinstalling macOS in their support documentation here: https://support.apple.com/en-us/HT204904
Options for reinstalling Windows can be reached by opening Settings, then choosing Update & Security, then Recovery. The Get started button under the "Reset this PC" heading will present reinstallation options. Other operating system troubleshooting tools can be accessed from the "Advanced startup" option on this same screen.
Microsoft provides more information about reinstalling Windows in their support documentation here: https://support.microsoft.com/en-us/windows/reinstall-windows-d8369486-3e33-7d9c-dccc-859e2b022fc7
An iPhone, iPad, or iPod can be reset by connecting it to a macOS computer and using Finder, following instructions in Apple's support documentation here: https://support.apple.com/en-us/HT201252
An option to reset can also be found in the device's Settings app by tapping General then selecting Transfer or Reset and then Erase All Content and Settings. The option to simply Reset will change settings back to their defaults, but does not sufficiently wipe the device. Apple provides more information about doing this in their support documentation here: https://support.apple.com/en-us/HT201274
Due to the wide variety of Android versions and differences in manufacturer configurations, there is no single set of instructions to reset a device that every user can follow.
Most Android phones will have some sort of "Reset to factory default" option in their Settings app, which is usually sufficient.
Google provides some information about preparing an Android device for a factory reset in their support documentation here: https://support.google.com/android/answer/6088915
Because every device is different, more detailed instructions for this process are best found on the website of the device's manufacturer or service provider. To this end, Google also maintains a list of device manufacturer and mobile carrier support sites here: https://support.google.com/android/answer/3094742
By policy the Help Desk does not offer assistance with operating system problems on non-University devices.
If you are having trouble with the re-imaging process, you can reach out to Technology Services' OnSite Consulting group. More information about their offerings can be found here: http://go.illinois.edu/OnSite/
Many 3rd-party IT businesses are also able to assist with problems of this nature. The University does not officially endorse any in particular, but the Help Desk maintains a referral list here: Help Desk, Tech Support Referral Resources