The good news…it’s deductible
According to the IRS, theft is deductible with the following considerations:
Loss of inventory.  There are two ways you can deduct a casualty or theft loss of inventory, including items you hold for sale to customers.
One way is to deduct the loss through the increase in the cost of goods sold by properly reporting your opening and closing inventories. Do not claim this loss again as a casualty or theft loss. If you take the loss through the increase in the cost of goods sold, include any insurance or other reimbursement you receive for the loss in gross income.
The other way is to deduct the loss separately. If you deduct it separately, eliminate the affected inventory items from the cost of goods sold by making a downward adjustment to opening inventory or purchases. Reduce the loss by the reimbursement you received. Do not include the reimbursement in gross income. If you do not receive the reimbursement by the end of the year, you may not claim a loss to the extent you have a reasonable prospect of recovery.
 
Leased property. If you are liable for casualty damage to property you lease, your loss is the amount you must pay to repair the property minus any insurance or other reimbursement you receive or expect to receive.
 
Separate computations. Generally, if a single casualty or theft involves more than one item of property, you must figure the loss on each item separately. Then combine the losses to determine the total loss from that casualty or theft.
 
SOURCE: IRS.GOV