Dead in Three Days (2006)

After a group of friends graduate from high school, they each receive a text which says they'll be dead in three days.  No one pays much attention to it since it's from an unknown number and all they care about is the graduation party that night.

They arrive at the party, which is massive, and have a great time.  Then Martin leaves to find a restroom and mysteriously disappears.  When he doesn't come back, his friends go looking for him and find his phone on the restroom floor. But there is no other sign of him.

When they go to the Police to report Martin missing, they are treated to a typical horror movie police response which is never take kids seriously, especially if they report worries of impending or recent peril.

The next day Martin is found dead and the police feel kind of bad about it. Soon the kids realizes that each one of them received the same threatening text message.  And wouldn't you now it, someone else is about to be killed.  It's an okay movie but nothing special.