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I posted this on the Joomla help forum, but it’s been less than a day and it’s already buried on the second page with no answer, so I figured I’d hedge my bets and see if anyone on here could help.

I’m somewhat new to Joomla and I have a few technical questions I’ve been trying to sort out.
I’ve been working on building this site for someone, using Joomla and one of the problems I’ve encountered recently is that that links to sub pages don’t work on the actual site.
I’m almost 100% they worked the first time I put them up, but now I get "The page you tried to access does not exist on this server. "
But the pages are all right there on Joomla, they were there when I started, because the person I’m building this site for had a number of page already there, some of them from another site (including the main page, which I’m overhauling) The sub pages were all there, save for one original one that I made; but I saved them, I’ve hit publish; the link is in a side menu on the main page, so I select which menu and give it the right name for the link; and it appears just fine in the menu on the main page, but you try and click it, it fails.
I’m positive it worked the first time, because I was really happy it worked and it all seemed to be working pretty easy; I probably wouldn’t have left it alone if there had been a problem the first time; but then a couple of weeks ago, I go to look it over, make some text changes and stuff, and I go to see how it looks on the actual site and….nothing.

Another snag is that, despite the owner of the site giving me administrator privileges (separate log-in/account from his own, but it’s supposed to be full access) I don’t have all the same editorial tools he has. There are many key function that simply aren’t there in my account that he has in his, which means I can’t do certain things we want to do to get the site how we want it. One of things being, uploading and embedding videos on some of the web pages. He did one, somehow, by uploading the video on the FTP and then putting an embedding code I found online – it worked, but I can’t seem to figure out how, because I can’t seem to reconcile where the files on the FTP are in Joomla.
But the main point is, certain folders and managers are missing from what I have when I log-in, compared to what the owner has when he logs in and I need to be able to access those functions; but neither I nor the own know why I don’t have these features, since I’m supposed to have…everything.

Lastly, somewhat small point, but something I definitely need solved; I can’t seem to put in links that lead away from the original website. The owner of the site has another site he wants the site I’m working on, linked to – but every time I put in the address, even the full address, starting with "http", when you click on the link, the address it tries to go to, puts in the full main address of the originating site and then the full address I put in. Just as an example, it’s like I’m trying to link from yahoo to Google, so I put in www.google.com into the field that asks for the address and enter the link; only the address it would take you to is www.yahoo.com/www.google.com.
I understand this could be potentially be useful for linking sub pages (although, not the ones I’m trying to link, since I don’t have a full address to them, that I’m aware of; and the process I’m trying to link them by, should work…) But I can’t find any options that establish the link as one that leads away from the main site. And for all I know, it’s because I’m missing the feature that lets you do that in the first place.

It may be that your account is set up to be an "Administrator" and you should be a "Super Administrator".

It also sounds as if there may be some SEF (search-engine friendly) URL rewriting issues. The missing pages issues might be a problem with the rewriting cache, so look for an option to clear it.

I’ve seen the "local site URL prefix" problem before. You may have to disable SEF rewriting or switch to a different SEF plug-in to fix it.