I've looked all around Windhelm both in the day and at night and have not found this so called Windhelm guard stood over a corpse that questions you the moment you get near. I've asked about rumors in both the dark elf Tavern and the main Nord Inn but neither have granted me the start of the quest and asking the stewerd in the castle is doing [censored] neither is asking the Jarl even if I start the quest to become Thane of windhelm. I don't know if I've [censored] my game up in Windhelm somehow but I really want to buy the house there and doing this quest is currently the only way I know how to. Help as soon as you can pretty please.

http://www.uesp.net/wiki/Skyrim:Blood_on_the_Ice#How_to_Start_the_Quest

You won't be able to buy the house if you don't participate to the Civil War.

I did, I killed Ulfric and have started the quest to become the thane of windhelm. ive helped the five people but I still cant find where to start the damn butcher quest

I have always started this quest by

The quest is extremely glitchy, and has many problems. You may have one of them.

Glitchiest quest in existence. I get the UESP article up every time and follow it to a tee. I had to go in and out of the city quite a few times to get it to start.

Because the quest had likely already begun when you did the final civil war quest, the guard's alias in MS11 was not swapped over to the new Imperial guardsman. In other words, you're boned, though it'll be fixed if you're on PC and use the Unofficial Skyrim Patch.

I'm having the exact opposite problem: this damn quest has always, ALWAYS, started in my games even when I didn't want it to. I had to mod it so that, at least, it doesn't start if the player is a DB assassin (makes sense, doesn't it?).

If you are right, and it's a possibility, it's probably too late already.

I think USKP handles re-instituting the missing guard as well, by creating an Imperial soldier anolog to the investigating guard.

BOTI is the glitch that keeps on glitching for us in the UPP team.

EDIT: After conferring with Arthmoor, USKP can still mend things if the guard disappeared because of the Civil War guard swap. If it's because the guard is dead, then it can't. USKP, among a litany of other fixes for BOTI, sets the guard to be essential and unkillable (as well as the Imperial guard counterpart), but that's no good if it's already dead and caused the quest to abort.

If you're not playing Skyrim on the PC, then... sorry, outta luck.