can't loc@te my account or mobile number or the type of zte 7.

I bought @ zte 7 from Best buy last month unlocked and now I can't find my account that was registered by Best buy . I have had problems since week one and I have gone back and verfied that a 2 year warranty came with the phone. Now my phone dropped just once and the screen is shattered and will not show up . What are my ootions?