Interest on personal loans is never deductible.
Interest on a mortgage may be deductible if you own the property, and pay the mortgage, and the amount of the mortgage is less than $1 million. You can only deduct mortgage interest paid in 2017 on your 2017 tax return. You would have to amend prior year returns to claim prior year interest.
If the lender did not send you a 1099-Int, you can use a year-end statement or contact the lender for a replacement.
You can only add interest you paid this year for your mortgage interest deductions.
If you think it will help other years, you can amend your prior year returns to add the interest.
A 1099-INT is for interest INCOME you receive on a deposit. If you pay interest on a mortgage, you get a form 1098 from the mortgage lender. Lenders for personal loans don't send a 1098.