You code checks to see if the player collided with a wall, you need to check to see if it collides with a specific wall, also you dont need the collision command at each iteration of the loop. I would go for somthing like,
;at some other point in the code, just once Collisions Type_Player,Type_Wall1,2,2 For Wall.Wall1 = Each Wall1 If EntityCollided(Player,Type_Wall1) = wall\en If EntityX(Player) > Wall\x# Wall\x# = Wall\x# - 0.01 Else If EntityX(Player) < Wall\x# Wall\x# = Wall\x# + 0.01 End If PositionEntity Wall\en,Wall\x#,Wall\y#,Wall\z# EndIf endif next