Ubuntu – dpkg: error: unable to access dpkg status area: Read-only file system

I am a newbie in this operating system

I installed Ubuntu 12.10 and I found it very interesting to use.

Then once I install chromn from ubuntu software I got

I/O Error

After that I could not install any application.

sudo apt-get install unrar
W: Not using locking for read only lock file /var/lib/dpkg/lock
E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem.

When I type

sudo dpkg --configure -a
dpkg: error: unable to access dpkg status area: Read-only file system

I have tried many solutions like

sudo apt-get autoremove && sudo apt-get clean && sudo apt-get autoclean
W: Not using locking for read only lock file /var/lib/dpkg/lock
E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem.

No used, I am really need your help.

Thank