What should I do if my tax payment particulars are not found against my name in the website?
The possible reasons for no credit being displayed in your Form 26AS can be:

Deductor/collector has not filed his TDS/TCS statement;
You have not provided PAN to the deductor/collector;
You have provided incorrect PAN to the deductor/collector;
The deductor/collector has made an error in quoting your PAN in the TDS/TCS return;
The deductor/collector has not quoted your PAN;
The details of challan against which your TDS/TCS was deposited was wrongly quoted in the statement by the deductor or wrongly quoted in the challan details uploaded by the bank.
To rectify these errors you may request the deductor:

to file a TDS/TCS statement if it has not been filed;
to rectify the PAN using a PAN correction statement in the TDS/TCS statement that has been already uploaded if it has made an error in the PAN quoted;
to furnish a correction statement if the deductor had filed a TDS/TCS statement and had inadvertently missed providing your details or you had not given your PAN to him before he filed the TDS/TCS return;
to furnish a correction statement if the deductor had filed a TDS/TCS statement which had mistake in the challan details;
to take up with the bank to rectify any mistake in the amount in the challan details uploaded by the bank.​