I donated locksmith tools that my husband hasn't used in several years as he has alzheimers and can't help me with the business numbers. How do I figure depreciation, et

These items may be allowed to be used as a contribution on itemized deductions if they were given to a 501(c)(3) organization.

If they had been used in his business and the cost had been expensed through depreciation then it's asking for the amount that was used as a depreciation expense on prior tax returns.

In summary:  If the item you donated was used in your business, so that you previously claimed a depreciation deduction for it, the amount of that depreciation deduction is what you'd enter here.  For example, if you're self-employed and bought a printer for $200 and previously claimed a depreciation deduction of $200 for it through your business, you'd enter that here.  If this does not apply to the item you donated, leave the accumulated depreciation field in the charitable contribution section blank.