Q: Flashing question mark on my Mac's screen at startup

While exploring internet over safari mac was not responding, i have cleared RAM using external S/W "Swipe memory" and entire mac was not responding than macbook was forcefully powered Off ( through Power button). After few second mac power button was pressed to power ON and found

1: Gray Screen

2: Flashing folder with question mark

3: No further progress in mac status.

On another PC Apple online support has been explored and follow the Apple suggested process https://support.apple.com/en-in/HT204323

but

* Recovery window`s --> Disk Utility and disk shows as 500.11GB APPLE HDD H... & disk5s1.

*No startup disk found named  "Macintosh HD"

At finally internet support suggests to reinstall the OS, but the problem i think is all the data will be erased. And i don't have any backup my data.

Now my question

A> how can i recovered HDD data before installing the OS ?

B> Is there any way to recover faulty HDD data using another MAC machine ?

B> Is there any device which convert SATA to USB ?

C> Is Linux compatible to access MAC HDD ?

please suggest.