Check the IRS website and update your bank information if necessary.
AGI is line 7 on your 2018 return and line 8B on your 2019 return. Refund is line 21a of the 2019 tax return. and line 20a for 2018
https://www.irs.gov/coronavirus/economic-impact-payments
Went to get my payment at irs site - entered needed info and bank info but response was info is incorrect per their records. Not so - I rechecked - even made sure low and high case letters correct.
@eekarts - additional hints:
social security number must have the dashes included XXX-XX-XXXX
date must have leading zeros if necessary (e,.g. April is "04" not "4')
standardize your address :
https://tools.usps.com/zip-code-lookup.htm?byaddress