What can you do alone at home without a cell phone or laptop? I'm bored
Reading, painting, cooking, doing sports, doing homework that you haven't done, doing things with your parents and friends.
You can read a bit or invent a story or something for a book or game that you can then (if you have a PC) do
A few tips that always help me.
Sort / count coins / money
Read
Fix something
Knitting / crocheting
I always got myself a piece of styrofoam (mostly you have something in the shed) and carved a little plane out of it.
Read
to paint
learn
create outfits
clear out the room