missing field in record

The best way: Open your CTD and the record settings in two tabs/two windows. Compare every used field in your record list view/filter.... if they are existing in the CDT as well. Sadly there is no versioning for record types. So i wouldn't have any smarter approach here. 

Actually there are 2 fields missing. So to add i again changed the table name and then enabled data sync, it says synced but the fields are not see in my record list .

"When you enable data sync, you are caching your source data in Appian. With a cache of your data, this means Appian will only have to execute queries from the cached data instead of the external source whenever you view or interact with the record data."
https://docs.appian.com/suite/help/21.2/records-data-sync.html

-> so the sense of data sync is to improve the performance of your data, not changing the strucuture.
-> you have to add the missing fields to your CDT again. ( the cdt you use for your record here)

tablename has nothing to do with it. The moment you changed the table name, it can happen that during saving procedure of your CDT a new table could be created. If the cdt is maintained properly to your data store it will update automatically.

you need a match between: DB Table & CDT and CDT & your Record type/CDT fields you like to use there.

"When you enable data sync, you are caching your source data in Appian. With a cache of your data, this means Appian will only have to execute queries from the cached data instead of the external source whenever you view or interact with the record data."
https://docs.appian.com/suite/help/21.2/records-data-sync.html

-> so the sense of data sync is to improve the performance of your data, not changing the strucuture.
-> you have to add the missing fields to your CDT again. ( the cdt you use for your record here)

tablename has nothing to do with it. The moment you changed the table name, it can happen that during saving procedure of your CDT a new table could be created. If the cdt is maintained properly to your data store it will update automatically.

you need a match between: DB Table & CDT and CDT & your Record type/CDT fields you like to use there.

Oh!  thank you Richard Michaelis.

So , when if my cdt is crct and my db is crct can i add the missing field in my record type ! Is this the crct/best practice !

your cdt have to be connected to a properly maintained data store.
-> add the field to your cdt and usually it will automatically update your table in your database. you don't need to work on DB level if you want to change CDT fields.