Hi Saberk, explorer.exe is an essential feature of Windows 10 so you don't have to download it. In case you encountered an issue when tried to launch it, I recommend you the following steps:
Open Start, type: CMD - right click CMD - press Run as administrator
Type in the following lines and then click ‘Enter” after each of them:
Dism /Online /Cleanup-Image /CheckHealth
Dism /Online /Cleanup-Image /ScanHealth
Dism /Online /Cleanup-Image /RestoreHealth
Then run the System File Checker utility:
Open Start, type: CMD - right click CMD - press Run as administrator
At the Command Prompt, type: sfc/scannow
This will check if there are any integrity violations
Restart your system