Only root User is able to open LibreOffice

Perhaps you have the same problem as this guy did.

Make sure your user owns ~/.config and everything in it.

This should do it:

sudo chown -R --reference="$HOME" ~/.config

It'll change everything in that directory to have the same owner and group as your home directory, which should have the proper values.

It looks like your username is not identified by linux to have enough privilege to run commands. A few things you should check like:

Make sure you are in sudo group with this command.

$ getent group sudo

It should show output as sudo:x:27:fayad

If you are not in it add the username with

$ sudo gpasswd -a <user> sudo

Crosscheck your /etc/sudoers by opening the file and confirming it has the following lines.

# Allow members of group sudo to execute any command

%sudo ALL=(ALL:ALL) ALL