I have a aspire one Acer and when I turn it on it says in a blue box, Harddisk Security and under it says Primary Master Hitachi HTS543216L9SLock. What can I do to restore it?

All solutions point to having to contact the drive manufacturer or laptop manufacturer. There is good explanation in the Tom's Hardware thread at the end, about a 'master password' ...

4.June.2014
Hard disk security primary master lock
harddisk security primary master lock

not sure if this link will help you out but have a look.... Acer Hard Disk security Google Search

You need access to a computer with Internet access so you can download a Hard disk password unlock program.
HARD DRIVE PASSWORD UNLOCKING - Purchase
http://www.hddunlock.com/purchase/ A-FF HDD Unlock Wizard (HDD Password unlocking - Free)
http://www.hddunlock.com/download/

This is known as a Boot Password. Cut power to the laptop, and remove the battery. If you can remove any panels from the bottom of the laptop, and locate the tiny CMOS battery, remove it for 3-5 minutes. It may even be under the keyboard. Once this is left out for 3-5 minutes, the CMOS should reset.

you have set a password for your hard drive and if you dont enter it the computer wont boot

If you changed the bios battery, or removed the hard drive, the machine will lock you out as it thinks it has been stolen. You will need to contact Acer to get this unlocked

you have a virus run a anti virus program; microsoft has free anti virus soft ware called security essentials....i use it and have had good results they also have a free malware scan you can download and run.

I think you should try to remove your motherboard battery. After removing the battery you will be able to access your computer. Please try this.

It sounds to me that someone has passworded the hard drive. If you do not know the password, there is no way to access the hard drive. The two options in this case are get the password from whoever put it on or uy a new harddrive. People usually password their harddrive in case it is stolen or lost, then nobody can read thei data or use their computer.

This is a "security" feature, to allow _only_ the person who knows the password for the encrypted disk-drive to use (and boot from) the unit. There's no way to bypass this security.