What is the ruling regarding my prayer and my clothes when some drops of urine fall on my clothes, and I am outside the home and unable to change them or wait for them to dry?

If you are certain that drops of urine have exited, you must repeat your ablution (Wudu') and wash the impurity from your clothes. If the location of the impurity is unknown, wash what you predominantly believe to have been affected. If you know that drops fall when you lift your leg to wash it, then wash it while it is on the ground. If you doubt that anything has exited, you are not required to investigate and you should disregard the doubt. However, if you are certain that urine has exited, you must wash what it has touched and repeat your ablution. You can also place a tissue to prevent the impurity from reaching your clothes.