Your question is quite ambiguous and it is is a bit tough to understand what exactly you mean. If your Yahoo profile name has changed and you want to revert to your old profile name, follow the descriptions as in the above response. In case it does not work for any reason, follow the below mentioned steps -
1. Hover your mouse pointer on your profile name. Remember to hover it - DO NOT CLICK.
2. In the resulting pop up, click on Account Settings .
3. Click on. Account Info .
4. Provide your password if asked.
5. Click on update your contact information
You should be able to change your name and other details.