After wearing my retainer for 5 years, do I still need to wear it?

I got my braces off 5 years ago and wore a retainer at night ever since. My smile was beautiful. A week ago my dog chewed it up and I got a new one. I told them it didn't fit and was pushing my teeth back and they didn't listen. They told me to wear it 24/7 for a few days and now my teeth look terrible. Can I stop wearing the retainer and my teeth go back to the smile I'd obtained that I've loved for so many years?