Welcome to the Atlassian Developer Community, @alok!
As your question, although related, is a different use case to that of the original post, I moved your question to a new topic.
The CQL needs to be modified to achieve what you want. You can try something like
/wiki/rest/api/content/search?cql=type in (page,blogpost) and contributor = "{accountId}" and lastmodified >= {startDate in yyyy-mm-dd} and lastmodified < {endDate in yyyy-mm-dd}
If you want to search for more content created or edited by more than one user, you can use contributor IN ("{accountId1}", "{accountId2}",...)
.
For more information about CQL fields, kindly check this reference.
Hope this helps.
Ian