disappearing administrative items

I don't quite know if this is an issue with the block.module but this is the problem, I don't yet know what the problem is.
I installed many new modules in a bulk to enhance my website (image,img_assist,multiblock,og,votingapi,views,advanced help). I noticed a crazy thing happening in my administrative page. Many links have disappeared !!! For example, under the "Site Building" I find only 'Blocks', under "Content Management" only 'Image galleries', under "User Management" only 'User Groups', under "Site configuration" only 'Actions'. And these are the only items shown. I'm outta my mind. Don't have a clue about what has been happening to my site, and I'm a week away from the deadline.
Please help, and help me fast.
I'm also getting this message on many pages "You do not have any administrative items. " And the content on any page is missing a lot of links. One more interesting thing, if I type the url in the address bar say "site/?q=admin/content/" I'm getting the same page (with missing links and contents) even when is some dummy value which does not even exists. My guess is that the urls are not being parsed beyond a certain level (please forgive my terminology, I'm a nube here).