Don't whip the hard drive like a horse, it's done nothing wrong.
Do this:
Go to System Preferences>Accounts.
Unlock the padlock at the bottom if it's locked.
Click the Plus symbol and create your own account.
Be CERTAIN where it says "New User" it says Administrator.
Also be CERTAIN the box next to FileVault protection is empty.
After you're done, just log out and log into your own account. Go to System Preferences>Accounts and click the old account then flick the minus symbol.