I have just reached the little village of Aleswell and the 'quest' to make them visible again involves a mage in a little ruined fort down the road, now I have spoken to the mage and he says 'just use the reverse invisibility scroll I gave you' to reverse the spell... problem is he HASNT given me a scroll.
Its not in my inventory, showing in my magic and also the quest hasnt updated... whats going on?

Is this a Vanilla/Official Ob quest as I dont think its a mod I downloaded.

I too have had a bug with that quest, but it is a different bug. When I go to the center of town to use the scroll, it does not work (the scroll is used up, but everyone is still invisible). The problem has to do with some mod I am running since I have successfully complete the quest before I had to restart my character files due to a computer crash (needless to say, I was running different (and a lesser number and more simple) mods).

load a previous save and start the quest over

If that doesn't work, click on yourself in the console and type additem 3001B 1

Cheers guys I will try the additem option as I have tried to load again and redo the quest

kudos x

Well I eventually loaded a game from about 1hour before and went back to Aleswell (Unholy Shadow the command code didnt work, I tried doing it in several orders like player.additem....) and yep, I got the scroll.... the problem nowis no matter where I am in Aleswell, even when the town name appears below me... the damn quest comes up saying I havnt cast the spell in Aleswell!
Another bug?

Also the scroll says Reverse Invisibility on SELF, is that right?

I recall having cast the spell in the veggie garden with the village chief (an orc if I well remember) in front of me, and it worked.
Try this, you have nothing to lose ...

Did you equip the ring?

Read this and make sure you've followed every step.
http://www.uesp.net/wiki/Oblivion:Zero_Visibility

I forgot all about that dumb ring!

First time I did this quest, all went well.. this time, he'd gave me the scroll but refused to give me the protection ring, and bad things happen when you don't wear the ring.. saved game.. I console killed him, took the ring, off his body,resurrected him, then went and made the people visable...all went well..Where there is a will there is a way...

I've done this quest many times (though it barely rates as a quest, you do bugger all) and had no probs. Dunno what was wrong, make sure to follow all the instructions to the letter. That goes for every quest.