sometimes appear a update alert icon on top right beside the wifi icon, but i can't update because this lock
by the way, first I ran the shell command, after this, I tried the update software
This could be a problem with broken dependencies. If you've added PPAs or other third-party software sources, various dependencies might be conflicting with one another.
All that said, now might be a good time to do a clean install of Loki, the latest version of elementary. (It looks like you're on Freya.) You'll need to do a clean install to get the latest version anyway, and setting your applications back up might be easier than trying to resolve the dependency problem.
A fresh install will get you back to the default software sources. Loki also replaces the Ubuntu software update tools with elementary's new AppCenter, which I've found to be simpler and more reliable.