If in windows using joomla you got problem of error #1045 - access denied for user 'root'@'localhost' (using password no) on running Php My admin in XAMPP.Then follow below step you will be able to solve this because i have also do this and my porblem get solved.
1.First Stop XAMPP
2. Goto to directory in which XAMPP has installed for example c:\xampp.
3. Then goto c:\xampp\mysql.
4. Run resetroot.bat .
5.Restart the PC and Enjoy.