Explanation:
Your adverb is most likely the word:
yesterday
Next is the explanation, it´s optional if you want to read it. It might confuse you though...
They usually end with -ly, but in this case you don´t have that...
Examples of adverbs that describe when an action occurred include:
Early: She arrived early for the meeting.
First: When I bake, I make cookies first.
Last: When I clean, I do laundry last.
Later: I will stop by later to see how you are doing.
Never: He never wants to go to the park with me.
Adverbs: An adverb is a word or an expression that modifies a verb, adjective, determiner, clause, preposition, or sentence.
This basically means that it describes: An adverb is a word that modifies (describes) a verb (he sings loudly), an adjective (very tall), another adverb (ended too quickly), or even a whole sentence (Fortunately, I had brought an umbrella).