Try searching on google "arma 3 godmode cheat". There should be a script somewhere you need to type. Turn godmode on and then off again, see if that helps

I tried several scripts and cheats regarding that, it didn't change anything. :I

I know this problem, I have had it often. Now saving and resuming using the main ARMA 3 way dosn't work, try going to the Shift-1 menu, saving your game in a safe place, then go back to the ARMA 3 main menu. restart the mission (Dont worry you will keep everything). When you enter it will give you an option of resuming an erlier save, select that option. You will spawn at the time of day and location of where you left off, invincibility will be gone and if an AI unit is acting up this will also reset him.