While it's likely no one will see the data, the only sure way is to replace the drive yourself and destroy the faulty drive.  If it's a hard drive, the cost (well under $100) may be worth the security.  
Hello. So i have had a issue with my hard drive and i was wondering, do you guys go though the files on the laptop. The laptop cannot boot to windows. I have some confidential things in it but its backed up. What happens to the faulty hdd. The hard drive has a failure i think and im mailing it so it can be replaced. I dont want my data to be checked or gone though because its confidential
My data for a repair