Apps Problem

I need help people.. recently, it seems that i have a problem updating my downloaded app. I can't install nor make n update. My signal is strong as i can access different sites and even watch you tube. I tried uninstalling apps since i thought it was a memory problem. I found out then that i cannot uninstall anything. Even thru Google play or the thru the settings. Please help. I am using Samsung Galaxy Note (GT-N7000)