I became blind to what was in front of me. For what reason — in this case a

complex series of chemical responses in your brain — you

didn’t pay any real attention, and it’s quite as tragic as a human being falling out.

The word “rusty” provided in other answers so far is probably the most idiomatic for the particular example provided.

The adverb neglected (also referred to as a verb to ignore) is an alternative.

“My French skills have been a little neglected… my French English skills have not improved at all.” Why did someone tell me that there was a mistake in my word? As

a younger Christian, please excuse the mess; I’ve been neglecting my chores.” ”