Facebook does not recognize any devices

Hello, a friend's Facebook account is experiencing a problem that even Facebook is having trouble solving. She has been unable to log into her account for several months now because Facebook is asking her to: please log in from a recognized device. Since I am on Facebook myself, I tried to log in from my PC using her ID and password - Facebook does not recognize my computer either (there’s no problem on my account!). Her Facebook page is visible to her friends, yet nobody seems to find any solutions. Can you help us? Thank you in advance.