Private key lost or deleted
Check your backups to see if it is possible to reinstall your private key.
If no backup exists, the only remaining option is to create a new CSR and apply for a reissue of your certificate through the Control Panel.
Please note that after a reissue with no changed data, the old certificate is not revoked automatically. If you wish to do so, please send us a revocation request after the reissue.
SSLCheck
Our SSLCheck will examine your website's root and intermediate certificates for correctness and report any potential issues