I want to track the fields History that getting changed. i want the report that provide the old value of any field and also new value of that field. Lets i want to track the keyword custom field. if changed the keyword than it will show the new value and also its old value.
The history reports provide this functionality - if you enable field tracking for a standard/custom object (e.g. Case) then when you create a report you can choose the type 'Case History'. This will show who made the edit, when the edit was made, the name of the field and its old and new value. The only caveats to this that I'm aware of are:
(1) You can only report on fields that you have turned on history tracking for
(2) large text area fields don't have the old/new values retained, so those appear as '-'.
(3) You can't report on the change history of custom objects that are the detail in a master-detail relationship.
I might be going out on a limb here, but I don't believe you can't use field history tracking in the way you described.
I would suggest keeping a 'shadow' custom object and use a before trigger to back up the fields to the shadow object. Then you should be able to write a report that uses both objects/sets of fields.
If you report requirements are slightly more complex however, you may need to write a VF page to do the appropriate 'report' generation.
Use New APp Which is Native.
Very Helpful for the Mater Detail History tracking on Custom Object. Which is not available. Report can be exported in PDF and Excel Formate