You should say:
– when it happened
– what happened
– how you changed your plan
Last month, I was going to have a picnic with my friends at a camping site on the outskirts of the city. Unfortunately, due to bad weather, we had to cancel our plan. In fact, we planned to have a picnic to refresh ourselves and to relax after the final term examination. Everything needed such as food, drinks and even a change of clothes was well-prepared.
I was so excited about this trip that I couldn’t sleep, and ended up chatting with my friends all night. However, on the next day, it was raining heavily, despite the fact that the weather was forecast to be nice and warm. As a result, we made a decision to put off our plans.
Instead, we threw a party at my friend’s house. We made some favorite dishes together, and then played cards. The ones who lost had to buy snacks for all of us. Surprisingly, we soon forgot all about our misfortune over the picnic. By the way, we enjoyed this party a lot, it helped us to chill out and get ready for the new term.
– a change of clothes: [expression] an extra set of clothes.
Example: In case it rained, we took a change of clothes so that we would have some dry things to wear.
– ended up: [phrasal verb] found myself in a situation that I had not expected to be in.
Example: After I was hit by a car, I ended up in hospital for three months.
– put off: [phrasal verb] cancel a meeting or arrangement.
Example: Plans to open the new supermarket have been put off until next month.
– threw a party: [expression] organized a party.
Example: We threw a party when my sister came to visit us from Australia.
– forgot all about: [expression] forgot completely.
Example: He enjoyed the concert so much that he forgot all about his problems at work.
– chill out: [phrasal verb] spend time relaxing and forgetting your worries.
Example: On holiday, I like to chill out on the beach and enjoy the fresh air.