That happened to me once on here actually. Me and some girl were talking about anime and other things we both like and I took a few minutes to make a protein shake for myself for breakfast for the next day and cut myself up a pineapple. Then when I looked on my phone to see if I had any messages here, I saw her message and tried responding but it said "You are not allowed to contact this user." and I couldn't go to her profile, either. I was so confused and had no idea why I was blocked, but it really hurt me :'( .