I've encounter the same problem today but my keyboard was working. But I can suggest you to try following things:
- Try to connect another keyboard.
- Maybe right click works. Have you try that ?
- Try to boot on Ubuntu Live cd. Normally it let will you reinstall (depends on how you've organize your files but it may be a solution).
- If you had ssh on your Ubuntu 16.04 (normally yes) and have another PC (Linux is best), you can with ethernet connect them.
Then try to know which IP are near you(try:
nmap -sP 192.168.1.0/24 on the another PC)... Normally not so much. Try to find which is good one or get their hostname (https://stackoverflow.com/questions/657482/how-to-find-host-name-from-ip-with-out-login-to-the-host).
After that, try to connect via ssh (If you have ssh on your Ubuntu).
On Windows you have Putty to make easily ssh connexion.
If you recover keyboard or a terminal, try several link on web who propose to solve problem:
ubuntu just mouse and wallpaper.
None of these links has solved my problem, but I make another thing:
I remove and reinstall
lightdm because it won't start. After, I simply do the following steps (Becarefull, you'll loose all preferences and settings in your programs if you do this steps, but it's essential.):
- Add a new user and connect with him.
- If that's working (sidebar, menu comes back), back up file of old user (without any
.* folder, like
.config !! Just data.)
- Delete old user. And remove his home (
sudo rm -Rf /home/old_user)
- Create once again your user as you like.
Good luck !