The SFC didn't report any corrupted files anymore. Thanks :3
As for the lock screen and the profile picture, I've seen the link you gave me, tried everything there and nothing works anymore (previously, changing the picture in the SystemData folder would change it, now it can't)
As for the bluetooth, I've tried sending the file directly and looking at the task bar, no such sign of any possibility of sending a file from the laptop but when i look at the instructions for the bluetooth, it says that i only need to right click the desired file and send it to the desired device (which doesn't show up when i right-click the file i wish to send).