LG ENV front screen

Hi everyone, i have a question about the LG ENv, i have asked around and found with many other LG phones, after the memory is full, the phone starts to have problems even after you delete alot of your stuff. Well i did that not thinking my new phone whould have any problems like that, and sadly enough the front screen now doesnt work. It will sometimes turn on again after i delete some stuff or turn the phone off for awhile. Anyone know how to fix this, i am verizon and didnt get the insurance plane. Although does anyone know if the 90 day return policy for best buy works with verizon phones?