hey there, firstly if you press your windows key(the key with the microsoft flag on) + R, it will open the run command, type
msconfig, then press startup tab, what is on there? anything look suspicious?, let us know, also have you tried another logon? also do you have any restrictions set for your logon? Right click ur taskbar, click properties, click the start menu tab, click customize, click the customize tab, scroll down and make sure the run command box is ticked. I will look up how to recover your shutdown button, in the mean time press ctrl + alt + del, press the shutdown button at the top and press turn off
