multiple if statements?

DvS_arduino:
i have to wait until he restarts his loop

You need to remove all the delay()s from your program. Have a look at how millis() is used to manage timing without blocking in Several things at a time.

When you have this sort of thing - lots of variables with numbers in the name

int LED0 = 2;
int LED1 = 3;
int LED2 = 4;
int LED3 = 5;
int LED4 = 6;
int LED5 = 7;
int LED6 = 8;
int LED7 = 9;
int LED8 = 10;
int LED9 = 11;
int LED10 = 12;

you need to learn how to use arrays as that will allow you to reduce your program size by 70% or 80%

...R