sounds like a windows problem through, rather than a physical problem with the laptop, so the bios sounds likes it’s working properly and starting the OS, which is all the bios does really. You can stop the boot up and get in to the bios, it should tell you what key does that as it boots, but you need to be quick. Got a feeling it’s F2 or ‘del’.
If you can’t get in in Safe mode, then it sound like you’d need the disc, but I’m not expert. There’s always Ubuntu if all else fails (the OS that is, not the tropical fruit drink), which she could try if it’s an old laptop, and just wants it for browsing).