Access denied to the computer system & entry to office

email correspondence can be taken as evidence in legal issues 

but in your case are you going to office regularly even though they does not allow you to enter the office but your presence is fore most creiteria to show that you are regular but the senior is not allowing  you in side the premises and about hr department not responding to your email write another email and wait for a week in mean time go to office and if possible give in hand written letter that you are coming to office and you are ready to attend the duties and state the reason and give in person to the hr deparatment head and also the senior most in the office and consult a lawyer who will give the correct steps personally 

These insurance companies have internal Grievance Redressal System.

Then there is possibility to escalate to Appointing Authority, MD, CEO, Company Secretary……………..

In your kind of situation majority of the employee make a blunder by writing anything or everything……………….whereas the representations should be carefully structured and drafted to suit interest of the employee and build favorable record for future.

The points to cover are: the employee is not absent, has not abstained/abandoned/ absconded…………..

The matter reported by you has been most probably reported as Compliance Issue, Indispline, Misconduct…………….and company/HR has prepared for separation…………hence the email id, entry to office is blocked………………..

The letter/show cause notice of HR should preferably be replied as per draft structured by a competent and experienced labor consultant/service lawyer………….

Without wasting time approach a competent and experienced labor consultant/service lawyer, show copy of your appointment letter, HR policy, Compliance policy, Exit policy, severance policy, emails sent and received, letter/show cause notice, give inputs in person ( without concealing any thing) and proceed under expert advise of your lawyer.

If you think it is appropriate you may send a PM and share the details of this insurance company, your designation, state in which you are located, state in which this company has its redg office/corporate office etc ………………..and there might be possibility of sharing some useful inputs.

Kindly proceed as deemed fit and suitable at your end.