hi i bought a laptop from ebay third owner first owner put password on it secound owner dosnt have password so i dont have it i cant install anything with out a password every time i try it asks for the password which i dont have so i have tried to change it and got this error I dropped to root shell during boot up, then used the password command, entered the new password twice and then received the message "authentication manipulation error". so now what ?please give me some things to try also i am new at this so i dont know where i am suppost to type commands at so if you could direct me with that too it would be greatful thanks ed

you can try this

I wouldn't trust a PC bought on Ebay.
Install a brand new OS instead.