how to fix my lenovo thinkpad can sign in but screen blank



Try booting to safe mode first.... hold F8 while powering the laptop on and choose safe mode. If you can log in that way I would suggest making a new user account and transferring files/shortcuts/etc over to the new user... If this works you'll probably want to scan for malware and so-forth if you're getting hung up while logging in it could be malware, an issue with auto updates, or many other things
 
hiya im on my lenovo thinkpad and my sisters one will turn on but when you log in it goes black but you can move the arrow and when you press ctrl alt delete , that menu will come up and you can only click one of them and they come up