Classic Outlook owns no indexer at all. Every Outlook search is answered by the Windows Search service working in the background - so when that service stops, is disabled, or was switched off by a 'speed up your PC' tool, Outlook search dies with it, silently and completely. This page checks the service first and restores it properly.
Of all the causes of dead Outlook search, this is the most mechanical and the most fixable: the worker is not running. The Windows Search service (its internal name is WSearch) builds and maintains the index that Outlook queries. No service, no index, no results - and Outlook rarely complains about it directly, it just returns nothing. The check takes two minutes and should come before any rebuild, because rebuilding an index whose service is disabled accomplishes precisely nothing.
The stopped-service fingerprint: blank status, Disabled startup - and an Outlook that fails silently.
You are looking for two facts: is it running, and is it allowed to start.
services.msc and press Entersc config WSearch start= delayed-auto followed by net start WSearchWindows Search almost never disables itself. The usual suspects are PC optimizer and debloat tools, old forum guides for making Windows faster, and occasionally an over-tidy IT cleanup script. The trade those tools make on your behalf should be stated plainly: indexing does use some disk and CPU, mostly while the PC is idle - and in exchange you get an Outlook that can search. On a modern PC the cost is small. On a very old hard-disk machine it is noticeable - but then the honest choice is 'slower idle PC with working search' versus 'search switched off', made knowingly, not by a checkbox in a cleaner.
A service that refuses to start is reporting, not sulking. Check that its dependency Remote Procedure Call (RPC) is running - it almost always is. Then read the evidence: open Event Viewer, Windows Logs, Application, and look for errors with source Search around the time you tried to start it. If the service starts and then stops repeatedly while trying to index, suspicion moves to the index data itself - that is the one service-side situation where the rebuild earns its place. If the service is missing from the list entirely, the Windows installation itself is damaged, which is system-file-repair territory, beyond a search fix.
The video checks this service on a real machine as part of the full indexing repair - watch the sequence once and the services screen stops being intimidating.
Watch Full VideoYes. Restarting it pauses indexing and search for a short while and then both resume; it does not touch your mail or documents. Expect Outlook search to be briefly unavailable or incomplete right afterwards, and expect the indexing counters to move again within minutes.
Automatic (Delayed Start) - that is how Windows ships it. The delay simply keeps the service out of the way during sign-in. Manual or Disabled means something changed it, and Disabled means Outlook search cannot work at all.
Then the service is innocent and the problem sits one layer up: confirm your data file is inside the indexed locations, read the Indexing Status counters for a freeze, and check your search scope. Each of those is its own page in this series - work them in that order before rebuilding anything.