I’m a self published author who purchased books to sell at store. Very few sold and I have a large inventory left after years. Can I claim a write down?

It depends:

• If your business will continue, then the inventory should remain on your balance sheet (and not be deducted).
• However, if you're winding down the business and have unsold inventory on your books, then you can take a loss after donating or disposing of the remaining inventory.