No text notifications on my Iphone 4/ deleting messages by itself

Recently my Iphone 4 has been having issues and I cant seem to figure out the problem. It has not been sending me any kind of notification of text messages. Whether it be on vibrate, or have the volume on. Ive tried resets, changing from custom to non custom tones, changed all of my settings for notifications.... Nothing is working. It doesnt show on my home or lock screen either. I have to keep checking my phone to see if any one has sent me a text. Im also having the problem of the phone freezing up before opening the text screens and then everything is blank. I can see who I have active texts with, but there are no texts left. I have tried EVERYTHING and nothing is helping. I NEED suggestions please