How I can resolve my problem with a part that don't move when i use bodi velocity?

Hey man, this one was a bit of a challenge to figure out and I'm not totally satisfied with the result but it works! After debugging the issue seemed to be making the PartType a ball. The solution to this is to make it a normal part and put a ball mesh into it. See the completed code below.

local Player = game.Players.LocalPlayer
local Character = Player.Character
local Mouse = Player:GetMouse()
local debounce = false

Mouse.KeyDown:connect(function(key)
    key = key:lower()
    if key == "q" and debounce == false then   
        -- Create fire ball mesh
        local specialmesh = Instance.new('SpecialMesh')
        specialmesh.MeshType = Enum.MeshType.Sphere
        -- Create fire ball
        local fireball = Instance.new('Part')
        fireball.Parent = Player.Character
        fireball.BrickColor = BrickColor.new("Deep orange")
        fireball.Shape = Enum.PartType.Block
        fireball.Material = Enum.Material.Neon
        fireball.Size = Vector3.new(3, 3, 3)
        -- Parent the sphere mesh into the part
        specialmesh.Parent = fireball
        -- Create a bodyvelocity
        local bv = Instance.new("BodyVelocity")
        bv.MaxForce = Vector3.new(math.huge, math.huge, math.huge)
        bv.Velocity = Character.Torso.CFrame.lookVector*20
        bv.Parent = fireball
        -- Position fire ball
        fireball.CFrame = Character.Torso.CFrame * CFrame.new(0,0,-5)
    end
end)

P.S Look into using Enum items rather than strings for cleaner code :)