Can't login to mysql

Hi guys,

Really confused by this.
I've set up an ubuntu server. Followed a few tutorials and got SSH, Apache2 and Webmin working.
then got php5 working to.
Then i got mysql ( apt-get install mysql-server)
i cant login ?? . I get >>>>>

root@BPserver:~# mysql -u root -p
Enter password:
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
root@BPserver:~# mysql -u root -p
Enter password:
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
root@BPserver:~#

Any ideas.
Is there an easy way to un install mysql and start over . I'm pretty new to linux

Any help appreciated

Cheers