When I logged in on the Admin Control Panel today I noticed that the SEO Tab has dissappeared(see below:)

[General][Forums][Posting][Users and Groups][Permissions][Styles][Maintenance]{System][SEO]

This has happened several times before, any clue how to get this tab back? and what causes this?

I use the pre-modded version of PhpBB SEO.

EDIT:
Nevermind, already found a similar post:)
Lost my phpbb seo tab in admin control panel

i want to add and remove 1 tab from control pnael can you please tell me the file with path, where to modify.
and other issue i want to make some changes in this file
you can check here
http://discussmatch.com/phpforum/viewfo ... f0e10d4392

can you please tell me which file i should modify.

tahnks