Wrong sentence=At the station I realized I left the tickets at home.

my corrected version=At the station, I realized I had left the tickets at home.

now what is the correct tense of the corrected version? i know it's past but what kind of past.
It's Past Perfect.
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and past perfect means? i know this is somewhat an unintelligent question but it would help me greatly if i had an easy and simple meaning.
You have something that happened in the past (I realized) and then you have something that happened even before that - that's when you use the past perfect (I had forgotten).