System factory reset Toshiba L300

Hello,
My mum turned on her laptop one day to find it wasn't working. It was saying to 'insert bootable disk'. I've done my research, and in BIOS the hard drive isn't recognised, it says 'none'. So I've been looking for a way to reset to factory settings, I don't have a recovery disk because the computer is new enough to handily not come with one, and I can't access the start menu or anything because it won't go past the bootable disk screen, therefore I can't make my recovery disk as per normal. Which is super helpful.

I have tried incessantly doing the press zero until the beep and the warning message but it doesn't work. I turn on he computer, while holding down zero, as soon as the beeping noise starts I let go the zero but no warning message or anything comes up, it just goes back to the bootable disk screen. I've tried holding in zero for longer and all variations of the method but nothing works. I've looked into creating a recovery disk on my laptop (Toshiba L750D) but everyone says that it won't work because different models and the recovery programs are encrypted for each specific computer.

Please help, I need to get this fixed, with as little or no cost as possible! I just want to do a factory reset!