To replace a lost Form 1099-INT, ask the bank or other financial institution that issued it to send you another copy.
A Wage and Income Transcript from the IRS will have the information from all 1099-INT forms that were issued to you, but in a different format. You can get a transcript free at the following link. You want a Wage and Income transcript, not a Tax Return Transcript.
You don't actually need the 1099-INT form. If you know the amount of interest that you received for the year, or you can find the amount from your bank statements, you can report the interest income even if you don't have the actual form.