Hi ,
This Particular thing Happen Because the Boot virus Diable the explorer.exe .So as to unable that follow three steps .
1)ctrl alt delete and
2)in winodws taskmanager click on show process from all user and then press ok .
3)Now Clik on file new task and Then Enter explorer.exe and hint enter .And then U r screen willl be back .After that plz make sure you scan u r system .So as to kill those virus
