Dell Laptop goes off

could someone please explain what might be happening, in brief, while working on my laptop, it suddenly goes off, and I cant get it to switch back on, so I take the battery out and after few seconds I try to switch it back on, no go, then
after a minute or so, the computer suddenly springs back to life, saying its doing a windows update,i had no notification of a windows update, so I cant understand whats going on here, and best of all , this is the second time this has happened

Maybe ur computer is set to auto update....that is why u dont get a notification and the computer automatically restarts to work on the updates