I'm sorry about the issue. Can you please tell me what happens when you go to the gmail.com website and type in / sign in your old gmail email address? Is there any error or message?
Please reply at the box below. Thank you.
When you are in Gmail, can you please click on the new gmail email address at the upper right corner (or click on the name or the big letter icon at the upper right corner), then click on Sign out option
; or you can click on the website below:
, then scroll down as needed, then click on option to Sign in a different account, or to Add account
, then type in / sign in with your old gmail email address, and check.
When you are available, please reply at the box below to continue troubleshooting. Thank you.