My HP ProBook was working normally, but it suddenly stopped booting and remained on the HP startup screen for a long time. After leaving it on, I got this message: "Boot Device Not Found. Please install an operating system on your hard disk. Hard Disk - (3F0). F2 System Diagnostics." I'm not sure what caused it or how to tell whether the drive is disconnected or has failed. Pressing F2 only displays "Entering System Diagnostics," then nothing happens, even after waiting more than an hour. The laptop was purchased through my school a couple of years ago, and I don't know the exact storage type or whether it's still covered by a warranty.
4 Answers
Since it’s a school-issued HP ProBook, contact the school’s IT department before opening it or replacing anything. They may know the exact model, handle repairs, or have records about warranty coverage. If the drive contains important files, avoid reinstalling the operating system until you’ve checked whether the data can be recovered.
The 3F0 message commonly means the hard drive or SSD has failed, although a loose connection can cause the same symptom. If the drive is removable, powering the laptop down and reseating it may help. If it still isn’t detected, it will likely need to be replaced and the operating system reinstalled.
If the SSD or hard drive is not soldered to the motherboard, replacing it should resolve the boot problem, but you’ll need to install the operating system again afterward. The exact replacement depends on the ProBook model, so check the model number on the bottom or inside the BIOS first.
First check the BIOS or hardware diagnostics to see whether the laptop detects the storage drive. If the drive doesn’t appear there, the problem is probably hardware-related rather than a damaged operating system.

F2 only says “Entering System Diagnostics” and then freezes there. I left it for over an hour without anything else happening.