How can I install it back if the app store of win10 system is missing?

The absence of the Microsoft Store app from a Windows 10 system is a significant disruption, as it is the primary conduit for obtaining trusted applications, updates, and certain system components. This issue typically stems from either the Store app being inadvertently uninstalled via PowerShell or administrative settings, or more seriously, from underlying corruption within the Windows system files or user profile. The resolution path depends heavily on the root cause, but a systematic approach beginning with the simplest solutions is most effective.

The first and most straightforward remedy is to use the built-in Windows tool for reinstalling default apps. Open a PowerShell window with administrative privileges and execute the command `Get-AppxPackage -AllUsers Microsoft.WindowsStore | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}`. This command queries the system for the Store package information and attempts to re-register and reinstall it for all user accounts. If this fails, the next step is to utilize the Windows Settings troubleshooting feature. Navigate to Settings > Update & Security > Troubleshoot, and run the "Windows Store Apps" troubleshooter, which can automatically detect and fix common issues with app registration and licensing.

Should these initial methods prove unsuccessful, the problem likely resides in deeper system corruption. In this case, deploying the System File Checker (SFC) and the Deployment Image Servicing and Management (DISM) tools is the appropriate course of action. From an administrative Command Prompt, run `sfc /scannow` to scan for and repair corrupted protected system files. Following this, execute `DISM /Online /Cleanup-Image /RestoreHealth` to repair the Windows system image that SFC uses as a repair source. These tools address the foundational Windows components that the Store app relies upon. After completing these scans and any required restarts, reattempt the PowerShell reinstallation command mentioned previously.

If all software-based solutions fail, the final recourse before considering a full system reset is to create a new local user account. Corruption is often isolated to a specific user profile; creating a new account and checking for the Store's presence there can confirm this. If the Store functions normally in the new profile, the issue is localized, and you can migrate your data. The persistent absence of the Store across all profiles, even after DISM and SFC repairs, indicates a profound system instability. In such a scenario, the most reliable solution is to use the "Reset this PC" feature under Settings > Update & Security > Recovery, choosing to keep your personal files while reinstalling Windows, which will restore all default applications including the Microsoft Store.