I filed an amended return but the IRS does not have record of it.

An amendment sometimes takes a bit to show up in their system. Have you looked on the IRS Where's My Amended Return?

Here's how you can check: How to Check your E-file Status

You will need to contact the IRS for information. It might be easiest to set up an account with them.

IRS Individual Online Account  

• Taxpayers with a Social Security number or an Individual Taxpayer Identification Number can create or access their IRS Individual Online Account to get information they need to file their return.
• With an IRS Individual Online Account, people can:
• View balance owed, payment history and schedule payments.
• Cancel scheduled payments.
• Get transcripts.
• View or create payment plans.
• See digital copies of some IRS notices.
• View key data from their most recently filed tax return, including adjusted gross income.
• Validate bank accounts and save multiple accounts, eliminating the need to re-enter bank account information every time they make a payment.
• View, approve and electronically sign power of attorney and tax information authorizations from their tax professional.