The context is different. "I might have made a typo" means that you probably made a typo. "I would have made a typo" means that you didn't make a typo but in a different situation/scenario you would have made the typo.

"I would have made a typo" is not right. It makes me think that you had the intention to make a typo but did not. "I might have made a typo" is better, because it makes me think that there is a chance you made a typo but aren't sure "I made a typo" is what you can say if you know for sure that you did make a typo