It sounds like you have issues whit sticky keys, that prevents you from logging in. (if that's correct then your only option are to remove the keyboard, from your notebook.
Google: How to remove keyboard "REPLACE THIS WHIT YOUR COUPUTER MODELNAME".
And follow some guide its fairly simple.In most cases you don't even need to remove screws.
go to http://www.aliexpress.com/ and order your self an new keyboard for that computer, and while you wait for it connect a external USB keyboard to the computer, and your able to log in.
You should clarify if you'r able to log into the computer, remote access it whit SSH or VNC. (then it would be easier for others to explain to you what to do.
if your able to log in you can try to open an new terminal
and type in
sudo nano /boot/grub/grub.cfg
in the the end of the file, and save the file
CTRL+X (type Y) and enter
In the terminal