Hdd password blocked. i am usind toshiba 40 gb hard disk, now when i boot my system it asks for a

Question

i am usind toshiba 40 gb hard disk, now when i boot my system it asks for a password and after 3 wrong attempts it blocks and i have to reboot and the same contineous. i by mistake blocked my hard drive with a passwor, now i want to know how can i bypass the password or erase the disk, so atleat i can use the hard disk.