Hey Vinodh, you have got a considerable score in GATE 2019 exam but it is not enough to get into any of the NITs.

Sorry to disappoint you with a score of 485 out of thousand in OBC category for civil engineering branch you have almost no chances of getting M.tech admission in NITs.

Last year a score of more than 600 out of thousand in GATE was required for clearing the cutoff of various NITs which is clearly more than what you have got.

I will suggest you look for some state universities or CFTIs.

Hope you will understand.

Please refer to the link below for previous year cutoffs of various NITs/IITs and other colleges:

https://engineering.careers360.com/articles/gate-cutoff