I changed my bitsat 2019 exam date and they said that the new hall ticket will be available at official website on 14 may at 8.00pm but I

Hello Student,

Please keep checking the website if it has arrived now as the website shows the notification of admit card for 27th May slot.
You can download your admit card here :-
https://www.bitsadmission.com/bitsat/bits2019ht/Default.aspx

If it's still unavailable, you must contact the authorities as soon as possible.
You can contact at the following numbers  on any working day from 9:15 am to 5:00 pm:-

Tel: 01596-242205, 01596-515330

You may also write an email at this email id:-
admnoc@pilani.bits-pilani.ac.in

Hope this helps :)
Best of luck!