Magnet damage to Macbook Pro

I was an idiot and put a magnet on the right hand side of my trackpad on my MacBook Pro! I took the magnet off quickly, after realizing what I had done, but it seems I was too late!

The laptop started making a weird sound so I switched it off, thinking it was the best thing to do. After a minute or two, I turned on the laptop again and it started up but with a folder with a question mark in the middle of the screen. I turned it off and tried again, but the same image came up.

I'm almost certain I've wiped it, but obviously I'm no genius. Is there any way to fix it without taking the laptop to Apple?

Unfortunately, the magnet damaged the data on internal hard disk, which is located near the trackpad inside your MacBook Pro. Data on standard Hard Disks is stored on the disk using patterns of magnetization.

You will have to erase and restore from a backup if you have one.

Do you need to take it into Apple?

Not necessarily. This is something you can do at home as long as you have installation media or a Time Machine backup.

When you see the screen below (any Mac computer, not just the iMac), it means that your computer cannot find the operating system (macOS) from which to boot. This can happen for any number or reasons like the OP putting a magnet on the HDD and basically erasing it or a drive failure (which affects SSDs as well) to good old fashioned user error.

Provided that you have a working drive, you can reinstall your OS.

• Boot from Recovery. ⌘ Command R. If your drive hasn't been completely erased, it will attempt to boot from the recovery partition on the drive.

• Boot from Internet Recovery. ⌘ Command ⌥ Option R if supported by your Mac.

• Boot from Installation Media. If your Mac came with installation disks, use the install CD1 or DVD to do a fresh installation. If you have access to another Mac (friend, coworker, etc.), you can download the installation media and create a USB installer which you can use to boot from (hold ⌥ Option while booting)

• Finally, you can take it into an Apple Store and they will install the OS for you for FREE.

The icon means it can't find an OS to boot from. You'll need to reinstall OS X and probably erase the disk.

Depending on the age of your Mac, you should be able to start Internet Recovery by holding alt-cmd-R on boot and following the instructions.