Upgrade to the latest macOS that is compatible with your Mac. Reinstall the latest macOS that was installed on your Mac (recommended). Release the keys when you see an Apple logo, spinning globe, or other startup screen. To start up from macOS Recovery, turn on your Mac and immediately press and hold one of the following sets of keys on your keyboard. If a wireless network is available, you can choose it from the Wi-Fi menu, which is also available in macOS Recovery. All you need is a connection to the Internet. MacOS Recovery makes it easy to reinstall the Mac operating system, even if you need to erase your startup disk first. If you use a Mac, you can install this professional Mac data recovery tool to recover data from Mac, external HDD, SSD, USB, SD/memory card, etc.
MiniTool Mac recovery software is designed for Mac users to recover deleted/lost files from Mac computers and Mac-compatible devices.
It supports the Mac data recovery on Mac OS X 10.9 (Mavericks) or later. The common files can be recovered with the free data recovery software for Mac, including photos, videos, music, emails, PDF documents, Office documents, RAR/ZIP files, game files, system data, and so on.