I changed computers and have 2 email addresses; it logs me in under my new email and shows I own one game I own over 30 games; I believe they are listed under my older email, but I can't log in under the older address. How do I find my lost games?

A long and arduous support chain.

Try a password reset on the other email maybe? If that doesn't work, then open a support ticket and explain your problem. After which you must wait for the movie "steven12105858 and the secret of his lost games" to show up this summer. (That's a joke, to be read as "it may take a while for support to get back to you").

It might be a good moment to prepare some purchase reciepts, If you still have some of course. Anything that can identify you as the owner of said account will speed up the process a lot. Good luck. Cheers

What logs you in with your new email? If by "it" you mean the GOG Galaxy client, I have no idea why it would log you automatically in with your new, wrong, email address, in which case I can only suggest uninstalling and reinstalling the whole client. Maybe you accidentally once logged into Galaxy with your new, wrong, email address, and ticked some box so that it always automatically logs in with that new, wrong, email address.

But before that, try also this:

1. Open your favorite web browser, even on a different computer or your phone or tablet, if needed.

2. Go to https://www.gog.com

3. Log into the web page with your OLD email address. It may require you to get a verification code from your email account to log in.

4. Do you find your games now?

EDIT: I missed the part that you "can't log in under the older address". Why not? Did you forget the password? Has someone changed the password? Does it give some error when you try to log in? Or you can't log in manually because the Galaxy client automatically logs in with your alternate email address?

You have two accounts. Log into the account that has your games, not the other one. You shouldn't really make multiple accounts anyway.