Dear member,
After submitting a letter of resignation, when you discovered that the HR portal is not working, then you could have taken the printout of your resignation letter and sent it by speed post to the company authorities. If you did not receive any reply, then what follow up did you do to get a valid acknowledgement from the company? Now, if the company says that they did not receive your letter of resignation, then what options do you have?
Belatedly, even now also, send the copy of your resignation by the speed post. However, now send it under a proper covering letter. Write that though the resignation has been submitted two months ago, you are yet to receive any acknowledgement.
By the way, the letter of resignation is always routed through the reporting authority. Do you have any communication with the reporting authority on your resignation? If yes, then attach it along with the covering letter.
Thanks,
Dinesh Divekar