Someone hacked my Yahoo password. How I can get back?
How to get the IP address of a person with whom I am chatting in Yahoo?

someone hacked my yahoo password. how i can get back?
how to get the IP address of a person with whom i am chatting in yahoo?

You should be able to get a new password, by going to the "I forgot my password" section of Yahoo, & answering the question you setup your Yahoo account with. First you should make sure there isn't a Keylogger on your OS, since this is the easiest way that hackers get your passwords in the first place. http://housecall.trendmicro.com
Is the best free online scanner. After you know your OS is secure & you have a secure browser
(try spyware guard & spyware blaster too!)

As far as finding out who hacked you, that will be tough, since there are hackers all over Yahoo Chat, just waiting for someone with less than secure internet settings, & a weak web-browser(like IE5 or 6) .
Firefox 2.0, is the best out, IE7 has been revamped & there are add-ons that can help secure you online better. Look for the add-on Keyscrambler, it
Will encrypt your username & passwords to keep hackers away. I protected myself from this years ago, by using dragon systems naturally speaking, by using voice commands hackers cannot steal passwords, since there are no keystrokes to log.


Pcfixinman

As indicated you need to contact Yahoo or go through the lost/forgotten password screens to get your password reset.

As for the IP, why would you need the IP of someone you are chatting with? Even if you could find it, all that it will tell you is the ISP that issued it. For any further info you would have to get a court order.