Hi @MonikaSutherlan ,
Are students getting the "access denied" message when they are trying to log into Canvas, or are they getting the message when they they are trying to access specific items in the course?
If they are getting the message when trying to access specific course content, it usually means that permissions, availability settings, or broken links are trying to direct students to something that they do not have permission to access.
The best starting point for troubleshooting that kind of issue is to use the "link validator" tool in the course. Have a look at this article: How do I validate links in a course?