M.Sc

Yes, you can apply for Ph.D after your Masters.

Yes, there is huge scope for mechanical engineering student, because Germany is a mechanical and automotive hub with majority of top automotive companies like Audi, BMW etc. Originating from there and also there are lot of manufacturing hubs.

Toronto University of British Columbia
University of Alberta
McGill University.

As you have completed M.Sc, now you can apply for NET or you can also do M.Phil.

Hi Jagarlmudi,
You must hold BS degree in computer Science or closely related field with excellent grades. Take the IELTS. German language test is not required, if the language of instruction is English. Germany is a budget friendly place for students. MS may cost around 500 to 1000 Euro per sem. Private universities will be expensive. Just check DAAD website. Details are mentioned.

Hi Puja,Yes ofcourse, you can do M.Sc in criminology in UNOM.

After M.Sc, you cannot join B.Tech, but you have a chance to join M.Tech, it's better you do Ph.D.