I entered my hall ticket number. But, it shows that it is an invalid hall ticket number. What should I do?
You must log in from the official website of the exam you are talking about.
Try to log in once again.
Even after this if it shows the same then go to the contact details on the home page and contact the authorities.
Please keep your other documents and details with you then might ask you about the same.
Don't panic, they will provide the necessary help.
All the best.!!