Assuming your old Google account still exists, go to
Google Contacts (on a computer or laptop is easier), make sure you're logged into the old account (if not, log out [click on your picture or the generic silhouette) and log into the old account), then export (More/Export) a Google csv file of all your contacts to your computer.
Then log out, log into the new account, import (More/Import) the csv file you exported. The new account will have all the contacts the old account had.
If you've already deleted the old account, and you don't have a backup file, you're in for a lot of typing.