If your talking about a bios, or a hard drive password lock, there is not much you can do.
Most people will not help you over this problem i am afraid, as there is a chance the laptop may of been stolen. You will have to phone up the company who made the laptop for help. You will be asked for proof that you own the laptop, such as a receipt, where it was bought from and a date it was purchased,and the name if bought by credit card ect. If you do not have these details the company Acer will not help you.