Mail app won't connect with my 'Virgin mail' email

Hi

I have successfully had my email working in Mail via POP3 for several years.

As part of installing another email provider, I decided to make changes and deleted the 'Virgin mail' POP3 account and set it up on IMAP. Since then it has not accepted any incoming mail and I have lost all items from my inbox! The connection to the server to send mail (via SMTP) works, but the 'connection doctor' says it cannot connect to the IMAP and tells me to 'verify that the username and password are correct'. Both are! The IMAP connection is set to run on Port 993, as advised by 'Virgin mail'.

My webmail is working fine. The problem is with Mail not with the provider.

I wonder whether there is some set up file that is still running with the old POP3 settings?

I have an iMac running OSX 10.9.5

Help appreciated.

Thanks

Chris