Right-click on the registry file and choose Merge.
Unzip and extract the appropriate registry file to the Desktop.
Download msiserver.zip (for Windows 11, Windows 10, and Windows 7.).
If the above steps do not help or if the Windows Installer service is missing in the Services applet, follow these steps: Fix the Windows Installer Service Registry Keys
Set the Startup type of Windows Installer to Manual.
In the Services console, double-click Windows Installer.
In the Trusted Installer Command Prompt, type Services.msc and press Enter.
Launch Command Prompt as Trusted Installer.
Resolution Start the Windows Installer service Instructions in this article apply to all versions of Windows, including Windows 11. The above errors may occur even though Windows is already in Normal mode. More help is available by typing NET HELPMSG 2185. Windows Installer is positioned as an alternative to stand-alone executable installer frameworks such as older versions of InstallShield and NSIS.The service cannot be started, either because it is disabled or because it has no enabled devices associated with it. New features include a GUI framework and automatic generation of the uninstallation sequence. Windows Installer contains significant changes from its predecessor, Setup API. The packages with the file extensions mst contain Windows Installer "Transformation Scripts", those with the msm extensions contain "Merge Modules" and the file extension pcp is used for "Patch Creation Properties". The installation information, and optionally the files themselves, are packaged in installation packages, loosely relational databases structured as COM Structured Storages and commonly known as "MSI files", from their default filename extensions. Windows Installer (msiexec.exe, previously known as Microsoft Installer, codename Darwin) is a software component and application programming interface (API) of Microsoft Windows used for the installation, maintenance, and removal of software.