Hi VISHAL,
Laravel can be difficult to get working with Shared Hosting. First port of call would be to check your admin panel to see if they provide you with access to any error logs. Something the logs are available from FTP, sometimes from an admin panel. Your error logs will tell you more detail to why your application isn't working.
I think the most common issues for 500 errors tend to be permissions related or missing php extensions. However there are a lot of things that could be stopping it.
Make sure your storage and bootstrap/cache folders have the correct permissions. Most FTP clients allow you to change your permissions through chmod. Make sure you take a look at https://laravel.com/docs/5.4/installation as well.
If you find your error logs, make sure they don't include any passwords and paste it here. Preferably share it via a https://paste.laravel.io paste.
Neil