If you are trying to open a wordpress page like http://www.yoursite.com/page/ and its showing you feed instead of the page content. Then you might have problem with some plugin, You can follow following steps to solve this issue.
- Try to keep up to date everything , wordpress, plugins, and themes if you are using any framework.
- Try to delete all inactive plugins.
- Deactivate all unnecessary plugins and delete them.
- Try to rename your plugins directory to something else like plu, and check if problem solve if yes, try to deactivate plugins one by one to see if page is working.
- Remove spaces before and after <?php ?> tags in your whole theme files.
This should solve issue for wordpress page showing feed instead of page.