Fix Apt in use

For above wait for the process to complete. If this does not happen run in terminal:

sudo killall apt apt-get

If none of the above works, remove the lock files. Run in terminal: (Note that this can seriously break your system.)

sudo rm /var/lib/apt/lists/lock
sudo rm /var/cache/apt/archives/lock
sudo rm /var/lib/dpkg/lock*

then reconfigure the packages. Run in terminal:

sudo dpkg --configure -a

and

sudo apt update