How to Change Password for deepin 2014

Hi as the title suggests, the reason being when trying to install something in terminal, ask for password and says my password is incorrect. It is the only one i have had for deepin and not sure why it doesnt recognise it now or how to change it. I have it on auto login on bootup, ive tried using chgpasswd prompt but permission is denied. Help a noob out please! :-[