I got a quest completed when I turned in the wrong guy. Is there no way to change this?

I didin't follow the wiki until towards the end, but I turned in the mage. Is there anything else I can do, or am I done?

Visit the city again and talk to the mage

He wasn't in his room. Where else does he go?

You kinda put him in prison. I WONDER where he could be.

if you sent the court mage to jail never fear, just visit the city a few more times and another murder will be committed, talk to the near by guard and continue from there.

A new murder never happened in my game (I don't know if it is because I usually fast travelled in and avoided it). I just read about it in the guide and talked to the wizard (although now that I have read, I found out I cannot clean the house because I had already bought all the upgrades.)

After stumbling around (becoming Thane, and getting the house furnished) I found him in in the prison. He only had the option to teach Destruction Magic.

I've been in game about 2 days. Should I leave for a bit?

Ok heres what u do.
If u turn in Wulfherth as culprit, he will be sent into prison and your quest will end. You can do something else(other quests, lollygagging etc) outside windhelm. Make sure you are outside windhelm though! Several days later, return to windhelm and a body of another woman NPC(can be any woman, voila giodarno etc etc) will be dead. Now talk to wulherth about the new killer(or jorleif first, whatever the quest marker points to) and patrol the stone quarters. You dont have to wait till night time on Loredas, just find Calixto whereever he is. Try talking to him, he will be tagged as 'BUSY'. Now stalk him and KILL HIM before he kills another woman.
Make sure you strike him when the woman(any woman) shouts HELP. Dont kill him BEFORE that, else you will have a bounty.

Yeah, ok. So I left. I went and did the Forsworn Conspiracy. I fought my way out of the temple. Now my follower (and wife) Aela is stuck in the temple.

This gets better and better.

Ok. The quest advanced. Thanks all.

Still svcks about Aela. Damn. Oh well. New follower? At least she won't die in the temple, right?

For me Calixto was 'Busy', I went into sneak mode since nothing was happening, get out of sneak mode, and he One Hits the woman as she is yelling Help.

THen maybe u should not do sneak mode. Just try walking along him normally but make sure your sword/dagger whatever fast equipment you use is fast enough to strike him before he strikes the woman. I saved Jora and she would have been dead if i delayed 1/2 a sec later. If u cant save the woman, reload. Or maybe u shld just let her die.

I just let her die and it did not really change anything. I will save her in my next play through though.