Hi @myamiami ,

More info is needed.  Could you please upload a photo of the screen?

At what point are you getting a long bar on the screen - When you first start it; if you try to access BIOS; etc.?

Your subject line says "system password," but is it for sure asking for one?  If it's asking for a password when you try to enter BIOS, there's what's called a password jumper on the MB.  Follow instructions in link carefully.  https://www.dell.com/support/kbdoc/en-us/000126390/how-to-use-the-jumper-to-reset-the-bios-password-on-your-dell-desktop-computer 

Optiplex 380 Tech Guide 

I have problems in login to my computer today and the massage is type the system password and yet none was given pls advice  the device is optiplex 380 series