New Energy Efficient Windows

Did you put the amount of the purchase on a credit card or did you finance the amount?  If you did either then you should have deducted the expense on your 2018 tax return.  If this is the case you will have to amend your 2018 tax return to claim the full amount of the expense.

This link to the TurboTax Help page  How to amend (change or correct) a return you already filed provides information on how to amend your tax return.   

Correct - financed. They gave me 11 months zero percent.

For tax reporting purposes, when you finance a purchase it is considered that you paid the expense in full, so you will deduct the full amount in the year you made the purchase.