bash doesn't keep history

I run Ubuntu 12.04, and for some reason bash does not keep my command history. the ~/.bash_history file contains only 3 commands that I typed a few months ago.

How can I fix this?

EDIT: here's the relevant content of my .bashrc:

# ~/.bashrc: executed by bash(1) for non-login shells.
# see /usr/share/doc/bash/examples/startup-files (in the package bash-doc)
# for examples

# If not running interactively, don't do anything
[ -z "$PS1" ] && return

# don't put duplicate lines or lines starting with space in the history.
# See bash(1) for more options
HISTCONTROL=ignoreboth

# append to the history file, don't overwrite it
shopt -s histappend

# for setting history length see HISTSIZE and HISTFILESIZE in bash(1)
HISTSIZE=1000
HISTFILESIZE=2000

It could also be that root:root owns your .bash_history (ROOT SHOULDN'T BE THE OWNER, YOUR USER SHOULD BE THE OWNER!), in that case you need to:

$ chown user:user .bash_history

This apparently could happen magically when you do sudo bash a lot!

Assuming you're using gnome-terminal??, if so maybe check the permissions on .bash_history. It should be -rw-r--r--

To do so in a terminal ls -la |grep .bash, all 3 files should have the above permissions. Otherwise try deleting .bash_history, restart & see if a history is then written

Note that the history is only written once the terminal is closed or quit.