According to
Bittrex's FAQ (there's a list in a link near the bottom), IDs from Nepal should be treated in the same way as other countries.
If Bittrex aren't verifying you, the best you can do is open support tickets, go on their Slack and onto some Bitcoin-related subreddits and see if you can get their attention.
Pretty much all crypto-related support teams are notorious for being unreliable, but only Bittrex can help you.
Apparently, Bittrex account closures over supposedly "suspicious" activity have become very common lately. It's definitely possible that Bittrex is shady and avoiding you deliberately.