Head to Control Panel > System and Security > Windows Firewall, then click Restore Defaults in the left-hand pane. Confirm you want to do so, and poof! Sweet stock setup achieved. (Be more careful this time around.)
The venerable System Restore acts kind of like File History, but for your system files and programs: It lets you return your PC to a previous, workable state if things go wonky. (Personal files aren't touched.)
System Restore points are automatically created once per week, or whenever you install a new app or update. To manually create a snapshot of your system—like say, before you attempt to install a crucial system upgrade—head to Control Panel > System and Security > System and then select System Protection in the left-hand pane. Click the Create button at the bottom and you're backed up.
If you ever need to actually make use of the feature, head to the same place and click the System Restore... button. A wizard will walk you through the straightforward feature from there.
Refresh and reset
Now on to the more dramatic options! Windows 8 includes new "refresh and reset" options that restore core aspects of Windows to their native state.
Of the two, Refresh is the kinder, gentler option. It won't touch your personal files, but it will wipe everything else. Settings, apps, desktop programs, you name it: All gone, replaced by the stock settings and apps that shipped with your PC. Watch out: Any personal files stored in your PC's Program Files folders will be plunged into the abyss, too.
Reset is the nuclear option, the tool of last resorts. Kill it, burn it, clean-install it into the ground. Everything you've installed, created, or changed on your computer disappears, replaced by a fully factory-fresh Windows installation. Make sure those important files are backed up!
If you've managed to break or clutter your operating system to those dire levels, you can find the Refresh and Reset options in Windows 8's Settings Charm. Open it, click Change PC Settings at the bottom, then select General in Windows 8's PC Settings menu, or Update and recovery > Recovery in Windows 8.1. Back up your data, kiss your kids, and select the option you'd like to use.
Go forth and tinker
And now you know all the ways Windows has your back. Install all those dazzling, incredibly useful desktop programs! Tweak those annoying PC irritations! Heck, hack your registry to make Windows leaner, meaner and faster than ever before! Even if you manage to wreck things completely, restored sanity is merely a reset button away.
Sign up for CIO Asia eNewsletters.