Sanjib Sikder <sanjibju2002@gmail.com> writes:

> Hi, 

Hi Sanjib,

> Org-mode is not working properly after I updated my Ubuntu 12.04
> yesterday. During the update, emacs also got updated. The .org files
> look like plain text file, for example, no tree structure, no folding
> etc.

Does `M-x org-mode RET' activate Org Mode after you've opened the file?
Do you have « ("\\.org\\'" . org-mode) » in auto-mode-alist? (check with
`C-h v auto-mode-alist RET')

-- 
Daimrod/Greg