To register campaign field we use a custom js code.
Last week for 6 days we had a problem with this code and our tracking code was not properly registered and we lost many information about traffic (many classifications have been recorded badly). Our tracking code is only query string based.
What do you suggest us in order to to recover these lost data?
Is updating the classification through the activity of classification import the only possible solution or are there other possible ways?
There is no data recovery solution for such a case. However, yes, you can utilise the page URL or query string dimensions (if you have them in the report suite) to create segments and calculated metrics to display performance of the missing tracking codes.