Usually I can recover data from a dieing hard drive, but sometimes it dies so quickly your data is just gone! So please back up you PC. I had a business client who had his whole business on his laptop and one day the hard drive crashes and everything was gone. He had to go to great lengths and expense to recreate his business docs because he did not have a recent backup.
There are Data Recovery companies, but it can cost 1,500 or more to recover your data. Most people don’t value their data that much
You can backup to an external hard drive (they all come with backup software) or you can use a service like Carbonite. I use Carbonite because it is really inexpensive, less than $60 per year. I like it because it is automatic and my data is saved offsite in the cloud. Very easy to recover a single document if you need to.
Oh, and Raid Mirroring is not a backup. Sure it is very dependable, but if you delete a file it is gone on both drives. You still need to backup a Raid drive. Raid is primarily meant to protect you from drive failures and the immediate lose of data.