There are a total of 13 butterflies in the game
4 in the hospital one of which is in a flashback and is missable.
-The first one you will probably come across is in a trash bag
-The second one is hidden behind a clock puzzle
-The third one is behind a door in a trash bag in the flashback scene
-The final one is in the freezer in the morgue area of the hospital
There are 6 in the high school.
-Butterfly five is locked behind a puzzle which the answer is
-The sixth butterfly is behind a flesh locker (this will affect your sanity)
-the seventh butterfly is in a room where you have to push a desk to jump up and reach it
-the eighth one is hidden behind a table after you get near the theater area. It's a little hard to see and the room has to ways you can enter/exit
-the ninth one is missable and is in the carnival flashback
-the tenth one is if you take the secondary path from the auditorium up the steps in a locker.
The last 3 are found in the apartments.
-the eleventh is on the first floor
-the twelfth is on the second floor in a chest
-The final one is available right at the end by
Sorry about no explaination for 11 and 12 but the apartments is a giant maze, but I hope this helps out