However you wish to change your race, you'll likely need some help from the GM as it is a pretty significant change in terms of your character concept. Here are some suggestions on how you can go about it.
1. Rebuild Quest
Players Handbook II introduces the idea of quests which can be completed to rebuild your characters (p198). Functionally the change is very basic in terms of rules - you simply change your ability scores, racial abilities etc. for those of your new chosen race. Things get a bit more complicated if you take racial feats/substitution levels/level adjustments, but the rules in PHB II cover that also.
If you can take time out from the main quest and the GM/other players are happy to go along with it, then this could be a really interesting, character-building (metaphorically and literally) experience.
In Savage Species it is possible to change race by spending XP/gold as part of a ritual - either that of Unlearning or of Vitality (p149-150) with the latter being much cheaper for changing to a race with no racial Hit Dice. This seems unnecessarily harsh if you are early in a campaign and feel like you've made a mistake choosing your character.
You didn't say what level you were so this might be out of your price range, but a Wish spell could have the desired affect, although it could have unintended side effects depending on how the GM rules on it. This is probably the least practice route for you unless you are particularly high level and can afford the 26,530gp cost. Again this is covered in Savage Species p150.
4. GM Fiat
If your GM is happy to allow you to change race, but doesn't want the faff of rituals or rebuild quests then they can fudge it as necessary. Maybe a witch curses you with being human, a spell goes horribly/wonderfully wrong or you drink a potion you shouldn't have. The GM has ultimate power, so if you want to make something work then just talk to them about it.
You may also wish to consider if you want to change race covertly (act like you were a Human all along and have everyone play along with it), or whether you want to acknowledge that your character has changed race - which will no doubt raise eyebrows among your companions!
There is no reason why you would lose equipment/permanent effects that aren't directly related to your race for any of these. You'd also gain any racial features of that race - such as feats or skill points. I'd strongly recommend reading Retraining/rebuilding sections of PHB II (191-199) to see how it works mechanically, but basically it's how you'd expect. You'd spend any new skill points or feats immediately and how you wish.
Over all, I get the impression that you are pretty early on in your campaign so I'd recommend options 1 or 4.