Sorry but I made a big mistake, I was desperate working with my LXDE VM without been able to switch to seamless mode, and following some forum topics I uninstalled from Synaptic the Guest Additions, but I also uninstalled these other 2 files:
I upgraded VirtualBox in the Host and when restarting the LXDE Guest I got:
"Failed to start de X server (your graphical interface) It is likely that it is not set up correctly. Would you like to view the X server output to diagnose the problem?
Log file /var/log/Xorg.0.log
config file /etc/X11/xorg.conf
confir directory: /etc/X11/xorg.conf.d
Failed to load module vboxvideo
no devices detected"
And now my LXDE VM goes directly to command prompt, that is terrible for me because I only use Linux via GUI.
So I guess I have to reinstall,
But from the command line I do not have Synaptic available and with Google I have not found a way to do it, so
How can I install those files and if I have to do any other maintenance task in order to have my VM back to normal?
My last VM backup is one week old and I have many new files in the VM.
Thanks for your appreciated help.