After I deleted an account can I retrieve the emails.
That really depends on how the account was setup in eM Client.
With IMAP or Exchange accounts the messages are stored on the server and eM Client just gives a cached copy of that. Deleting the account from eM Client will not affect the message store on the server, so going to another email client and setting up the same account will sync all those messages to the new client.
With POP3, usually if you delete the account from eM Client, you permanently delete the messages because they are stored on the computer and not the server. There may be a few left on the server depending on the POP3 settings, but generally they will be deleted and not retrievable at a later time (unless you have a backup).
To find out which you are using, go to Menu > Tools > Accounts and see if the account has an IMAP/EWS tab or a POP3 one.
Thanks for your prompt response. I’ll give it a go. Cheers