Oblivion:Bruma Recommendation

Quick Walkthrough
# Speak with the leader of the Bruma Mages Guild, Jeanne Frasoric. She needs help in finding a mage who has been missing for days.
# Either look for J'skar by yourself or get help from Volanaro, his mischievous friend.
# Tell Jeanne Frasoric that you have found J'skar to obtain her recommendation.

Detailed Walkthrough
Bruma Mages Guild
Talk to Jeanne Frasoric in the Bruma Mages Guild. She will request that you find J'skar -  a missing mage who hasn't been seen in days. If you can find him, you'll have your recommendation from her. There are two possible ways to accomplish this quest.

Working with Volanaro
Talk to Volanaro, also in the guild hall. If his disposition towards you is at least 70, Volanaro will agree to help you find J'skar if you help him play a prank on Jeanne. He wants you to steal Jeanne's Manual of Spellcraft from her desk upstairs. He'll even teach you the Minor Latch Crack spell (a more efficient version of Open Easy Lock). Go upstairs to Jeanne's room, unlock her desk, and steal the Manual of Spellcraft from it. Jeanne's copy of this book is unique; other versions of the book will not work for the quest. Be sure you are not caught taking the book, or else you will be suspended for stealing from the guild. Return the book to Volanaro who will tell you to meet him in the living quarters after 10pm.

Wait or return around 10pm to the living quarters downstairs. Find Volanaro in his room and speak to him. Once you're ready, ask him about J'skar. In a flash, J'skar will appear before you. Apparently the two were just having some fun with Jeanne, and he was invisible all along. Report to Jeanne that you've found J'skar in order to receive her recommendation.

If you want to get the Minor Latch Crack spell without pranking Jeanne, just agree to Volanaro's plan, don't steal anything, and then follow the walkthrough below to find J'skar yourself. Even if you don't steal Jeanne's book after receiving the spell, Volanaro will still remark on how great the prank went.

Searching for J'skar on your own
The easiest way to find J'skar is using Detect Life and looking for the only purple glow not associated with any visible person. J'skar is most likely to be in the basement. You may also bump into an invisible barrier from time to time, and the tool-tip at the bottom of the page will tell you it is J'skar. If you speak to him while he is under the Chameleon effect, J'skar will say, ''"Shhh! Go away! You'll ruin everything!"''

Once you have found J'skar, cast Dispel on him and he will reappear. The apprentice-level spell Dispel Other can be purchased from Alves Uvenim in Leyawiin; at journeyman level in Mysticism, Volanaro can sell you the Greater Dispel Other spell. If you are not able to cast a spell, you can instead use a Dispel Other Scroll or a Staff of Dispel. The scroll and staff can be found in random loot from as low as level 6 and the scroll is sometimes available from some stores that sell random leveled scrolls, such as the Mystic Emporium in the Imperial City Market District.

Once J'skar reappears, he will complain that you're "no fun at all" but agrees to tell Jeanne that you found him.

Notes
Until this quest is completed, Volanaro is scripted to cast a Chameleon spell on J'skar every evening. The spell (FormID  ) provides 100% Chameleon for 2880 seconds (as with all spells, the duration is real time; for standard game settings, the spell will last 24 in-game hours). It is possible to get in Volanaro's way when he is casting the spell, resulting in the long-duration Chameleon spell being cast on you instead. For this to happen, you need to be standing in between Volanaro and J'skar (who is invisible) when they are both in the Mages Guild basement, shortly after 8pm.
If you want to avoid adding to the "Items Stolen" counter, you can simply select "take all" when opening the desk in order to take the Manual. Note however that if you are attempting to gain access to the Arcane University, you will pick up at least two other stolen items (two Black Soul Gems in Cheydinhal Recommendation) in the process anyway.

Bugs
 
This is most often solved by waiting until noon the next day and then speaking to him again.
 
In this case, follow the second option detailed above and Dispel him yourself to complete the quest.

Journal Entries