been sending series of mails to whogohost since december without getting any response as i needed to log in into the client area

I had click on the forgot password tab to retrieve my password but never got any response from the system
since i needed to log in into the client area to renew the domain

I needed to renew a domain which was almost getting expired

This doamin just got expired and whogohost is yet to send me an invoice for payment

any agent of whogohost seeing this should treat my case,else i will advertise this on google

FYI...I have called whogost without any result as a result of the calls
charted with customer care
sent a support ticket and mail without getting a response from whogohost

May I enquire if this domain is locked and if so, can you at least make sufficient contact for them to unloack it for transfer?
If your domain has indeed expired, it might begin to get expensive to get it back but you should be granted a renewal grace and registry redemption period which might incur a domain name recovery fee.
Is it a .com registration and have you attempted to reach out to ICANN on the basis that your registrar has gone missing? There might be workarounds but it will not be quick.
As it has only just expired, your website will be live for a few more months.
If in need of a new cheap domain with free private registration, visit https://hostdoc.co.uk/domains. Free hosting with every domain purchase.

Good luck.