If you don't have a Windows 10 installation media, you can download the Windows 10 recovery USB image from Microsoft. However, you'll need to use the Media Creation Tool to create a bootable USB drive.
Microsoft provides direct download links for Windows 10 installation media, but not for a recovery USB drive specifically. However, you can use the Media Creation Tool to download the Windows 10 installation media, which can be used to create a recovery USB drive. windows 10 recovery usb download