Once a players name is typed into "script.Parent.Parent.Player.Text" then it finds that user in Players. There are no errors so I tried putting prints in every line and it stops after local player = game.Players:FindFirstChild(user). It doesn't return/find the player I think. If it did then, it will change the players kills to whatever I enter in "Number".
function kills()
if script.Parent.Parent.Player.Text == "" then
else
local user = script.Parent.Parent.Player.Text
local player = game.Players:FindFirstChild(user)
if player then
player.playerstats.PlayerKill.Bandit.Value = script.Parent.Parent.Stats.Number
end
end
end
script.Parent.MouseButton1Click:connect(kills)

2 comments
Make sure your hierarchy is correct. Could you possibly take a picture and give it to us?
Are there any errors in the output? Try printing player.Name as well, see if anything comes up or if that ends up erroring out.