Have a look at the PlayerPrefs class - http://unity3d.com/support/documentation/ScriptReference/PlayerPrefs.SetInt.html

something like this should do the trick:

Set the player level when a new scene is loaded to save the number of the last level to be loaded on the player's machine:

PlayerPrefs.SetInt("SaveLevel", Application.loadedLevel);

And call this when the game is first started to get that same value:

savedLevel = PlayerPrefs.GetInt("SaveLevel"));

hi, may i aske? how do i declare savedLevel?