Hello ,
I install in my computer Xampp apache becouse and i want to use mysql. I made all settings and when i try to log in in phpmyadmin I can’t do this becouse an error message apair saying" 1045 error cannot log to server ". After this I open shell and i type there the following code " mysql> GRANT ALL PRIVILEGES ON . TO user@localhost AFTER THAT ,I PRESS ENTER AND ON THE NEXT ROW APPAIR AN ARROW AND NEAR ARROW I TYPE "WITH GRANT OPTION;
AFTER THIS PROCEDURE ON THE SHEEL APAIR THE NEXT MASSAGE "#1045 ERROR<28000> Access denied for user ‘root’@‘localhost’ (using password: NO). Please help me to fix this problem. Is so important to me.

You should not have needed to grant any user permissions and I have installed XAMPP loads of times without a problem.
If you want to setup a user you can use the XAMPP interface or edit the password file.

Have you started Apache and MySQL from the XAMPP control panel?

From memory the standard user is Root without a password

I recently installed XAMPP and had problems getting everything running from the XAMPP control panel until I right-clicked on some file (I think it was xampp-control.exe) and chose to run as administrator. After I did that everything worked fine. There is no MySQL password on the default installation of XAMPP. Once everything is running you can access MySQL using phpMyAdmin without concern about credentials.