I need help

No problem. If this is a windows passwod, you will need to boot into safe mode by hitting the F8 key at start up. Once you're in safe mode, log in under the administrator, from there you can go into user accounts and clear the password.

Now if this is a bios password, you will need to contact Dell support directly. You will need the service tag and express code from the bottom of the machine. They will give you a master code for the machine to get you past the password. They also require that you are the registered owner of the machine in their files. This is easy to do, there is a tag in the left hand corner of Dell's support page that reads register ownership. The link bellow will take you to the contact info you need to call Dell support.
http://support.dell.com/support/topics/global.aspx/support/dsn/en/document?c=us&dl=false&l=en&s=gen&docid=E21A18454B4A6550E030A68F27286358&doclang=en&cs=#1