There are some bunch of custom and standard fields that are not being used in my sandbox. I know how to check for one field(Delete it and if it says it is referred somewhere. If it says so, it is being used or else it is not) . But if there are more fields which are not being used , how can i come to know that? Trying above technique would take long time. So please provide me any easy way to do this
It depends on what you mean by not used. If by not used you mean no data then you could either run a report if it is a small amount of fields or you could use the FieldTrip app. The app will give you a run down of how often fields are used. It is on the appexchange and I think it may be free. If you are not looking for whether the field has data and are more concerned about the code, formulas, etc the field is used in then you could try Eclipse. In Eclipse if you go to your workspace and then press CTRL+H and type in the name of the field, the places where that field is referenced should pop up in the results.
I use the 'Metadata Search" free app from the app exchange. Install it in the org you are working in and it will list all components that reference the field.