The Settings app in Windows 10 offers you a search bar that let you quickly search for any setting. But some users have reported that the Windows 10 Settings Search Bar is not working, with the settings themselves not getting indexed. Even if your search using the taskbar search bar, you will not see any Settings listed. It may be not finding Control Panel or Settings app items or simply show no results. If you are facing any issues, try this solution.
Windows 10 Settings Search not working
First of all open your Computer folder, right-click on your system Drive which is C, and select Properties. Ensure that the Allow files on this drive to have contents indexed in addition to file properties box is checked. If not, select it and then select Apply changes to subfolders and files.
Now, open the following folder location:
Here, right-click on the Indexed folder, and select Properties.
Next, click on the Advanced button and check the Allow files in this folder to have indexed in addition to file properties setting.
If it is already checked, uncheck it and click OK. Then again check it and click OK > Apply and exit.
Restart your computer and see if it has helped.
See this post if Cortana and Taskbar Search is not working.