Create a new user account for yourself, move your documents etc over, then delete the old not working one. Running the system file checker, sfc /scannow might fix the BSOD problem. It almost sounds like a ransom ware infection I worked on a while ago. instead of your desktop you got a fake screen saying you were doing something illegal on your PC and had to pay a fine to get access again. I did an offline scan which only got some of the nasty's. On the next boot all I got was a white screen. Couldn't launch task manager either. After another scan with Windows Defender Stand Alone I was able to get back in and recover her files. I ended up nuking her install and doing a clean install just to be sure it was clean. That PC only had the one user account on it. I'm not 100% sure your in the same situation but the symptoms are similar.