Since you have tendered your resignation letter and also do well serve the notice period, you have already performed your duty.
The employer ought to find a person to handover or for a replacement within this notice period, otherwise what the relevance of serving a compulsory notice period is?
If the employer wilfully do not provide any person to take the handover or engage a new person it simply subjected itself to loss and the employee is nowhere at fault, especially when the employer remain silent after the resignation letter!
You please send your ex-employer a strong reply letter through your Advocate and request him to discharge your salary along with all other document which you are eligible to get within an ultimatum. And if require please do not hesitate to approach the Court.