[Trisquel-users] need urgent help with apt tools

[apmwnq]

i am running trisquel 5.5 on my laptop and today i decided to update my  
system with the command line
typed " sudo apt-get update " and a few seconds later i by mistake pressed  
the key binding "ctrl+z"

in response the terminal showed me this
E: Could not get lock /var/lib/apt/lists/lock - open (11: Resource  
temporarily unavailable)
E: Unable to lock directory /var/lib/apt/lists/

what do i do to fix this .
any input is appreciated thanks guys and "viva le gnu/linux".