Every program i open closes so i cant perform a thing!

Hello,
it started when google chrome closed on its on. after that it was all the windows i opene,even on the dekstop constantly shutdown option apeared.then the mouse started getting stuck and when i typed(with was very rare)some letters appeared and some didnt.anyhow i managed to run a virus scan through windows defender but no threat was detected! What should i do when now i cant even login my laptop?

it is windows 8.1 intel core i5