An amended return must be prepared on a Form 1040X which can only be printed, signed and mailed--it cannot be e-filed. It takes 3-4 months for the IRS to process an amended return. If you are getting a refund, the IRS mails a check to the address on your return.
https://ttlc.intuit.com/questions/2566895-what-does-it-mean-to-amend-a-return
https://ttlc.intuit.com/questions/1908543-do-i-need-to-amend
It is a good idea to use a mailing service that will track it, like UPS or certified mail, so you will know it was received.
Wait about 3 weeks from mailing and you can check the status of your amended return:
https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1
https://www.irs.gov/filing/individuals/amended-returns-form-1040-x/amended-return-frequently-asked-q...
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**