Is it just as simple as new hard drive + new apple OS?

basically yes

First out what model? Example (early 2012)
You need to retrieve anything on the HDD?
What makes you think it failed? Because alot of macbooks have trouble with the SATA cables, fixed this issue for my GF.

I'll ask my dad when he got his. He said he took it to apple and they told him it was a failed hard drive and wanted $500 to fix it so I have no idea what is wrong.

I'm sure if I were able to salvage anything He'd be happy but im gonna say he's already assumed it's all gone.

500$ to change the hdd thats ridiculous!
If vs has a mechanical hdd it would be a great idea to upgrade to an SSD this time.
But honestly it can easily be broken SATA cable and a functional hdd.

As for retrieve the data you would need to change it first anyways.

This post was edited by ZwiX on Apr 7 2017 06:48pm

My laptop HD failed 2 years ago.

I found an old one in my closet, put it in, windows

Still have a laptop