restart everything on level 1 load

within my game if you run out of time or complete the game you have the option to go back to level 1 and start again but when you do this level 1 flashes up for about 5 seconds due to it being destroyed at some point within the game. when i restart level 1 i would like the countdown timer to restart as well as the score but i cant seem to work out how to do this. i know about DontDestroyOnLoad but im not sure if this is what i want, all i want is some code i can put on my level 1 saying basically on load, reset everything to its original. please could someone help?