Hello dear
You can participate in nptc
And here are the steps to follow
Get a good score in GATE.

Apply for NTPC.

Participate in GD and Interview.

Get Police Clearance Certificate

You can absolutely get into ntpc and also railway ntpc
There are various vacancies during month of December for diploma trainee in civil, mechanical and csi. Keep updated with their website

You can also give rrb ntpc entrance exam for criteria of higher secodory level post

Railway Recruitment Board (RRBs) has released RRB NTPC Exam Date on September 5, 2020. RRB will conduct all railway exams like RRB NTPC, RRC Group D, and RRB Ministerial And Isolated Categories from 15th Of December 2020. A detailed exam schedule for RRB NTPC 2020 exam will be announced very soon. Railway Board had notified 140640 vacancies for different examinations before the pre COVID-19

Hello Abel Tete , Yes, of course you are eligible to get a job in NTPC after completing Diploma course. You can apply for Diploma Trainee post. Candidate Having Full time regular Diploma in Mechanical / Production Engineering with minimum 70% marks. Candidate Having Full time regular Diploma in Electrical / Electrical & Electronics Engineering with minimum 70% marks.

Hope it will be helpful for you :)