My b2evolution Version: Not Entered
Ok, ive seen how most people prefer to use phpmyadmin, or the php interfaces, but for someone like me who is lazy, the mysql commands are far faster and easier.
Things you will need to know:
DBName
DB Prefix
For mine, I will assume: DBName Evolution, with a prefix of Evo_
use Evolution;
update Evo_users set user_pass=MD5('YourNewString') where user_login='loginyourefixing';
To me thats alot faster and easier than having to create a php page/function or whatever.