Being tortured by a picture frame

Day:2

I woke up.I knew I had to go to school. It was spring,I like spring.So I got up and did my normal routine-PHONE!I saw that I got a message from a locked number!
Anonymous:
You shall be gone before moon finishes its journey...
-Your worst nightmare...

I thought that some of my friends,I have three only but don't judge me,was messing with me.But still I did not know what that meant.I arrived at school and everyone was so weird.On lessons the teachers were so nervous!They were sweating,they were so unpacient...Every single one of them was looking at me with some kind of fear in their eyes.But I gotta admit it was a good school day.We did nothing they just gave us simple tasks.I still had the text on my mind.I remembered that my friends don't like to mess with people.To do pranks and stuff.So that's why I tried to reply on that text but this came up:
You can not contact this number.

What was that supposed to mean?

On lunch I was sitting with my mates Kate,John and Burkelly.I told them what happened.They were just looking at me strangly,and finnaly Burkelly said:''You know,I am really worried...I still don't get why would anyone say that to YOU!You and I and Kate and John don't really like other people.We don't even speak to them.And why would ,who ever that is, use future perfect?''Kate said :''It's like they know that you are afraid of 'shall'.''John was just staring at me.I was freaked out. When I told them about my dream they just laughed.And the day ended so quickly,unfortunantly the night began earlier than before and I was really affraid.