Windows Update Diagnostic
"Windows Update isn't working" covers a lot of genuinely different problems, each needing a different fix. Answer honestly and you'll land on the guide built for what's actually happening, rather than one meant for a different stage of the process.
Did something break or stop working right after an update installed?
This is a different problem from Update itself misbehaving — the update did its job, but the result caused a new issue. Go straight to our guide on an update that broke something, which covers identifying and uninstalling the specific update responsible.
Move to the next question to narrow down which stage it's stuck at.
Is it stuck on "Checking for updates," or does it find one and get stuck after that?
This is a specific, well-defined problem with its own guide: Windows Update stuck "Checking for updates". If you're specifically on Windows 7, use the Windows 7 version instead — the exact steps differ enough to matter.
Good — the check itself is working. Move to the next question.
Once an update is found, does it fail to download at all, or does it download but then fail during install?
Our guide on an update that's found but won't download covers this stage specifically — connection checks, storage space, and the metered-connection setting that quietly blocks downloads.
Move to the last question — this is a distinct pattern from either of the above.
Does the same update keep failing and reinstalling itself over and over?
This exact pattern has its own guide: an update that keeps failing and reinstalling, which covers the SoftwareDistribution and Catroot2 reset that fixes the large majority of these loops.
The closest broad starting point is our guide on an update that's found but won't download or install — it covers the widest range of general causes and is a reasonable place to start from scratch.