Maria , a common mistake while finding corelation ids is the way it is copied from the browser it generally comes with an extra space at the end. So when we search this using notepad or any other log reader using Ctrl + F it does not come up. Can you confirm this and let us know if the id is copied without spaces.
It suggested you copy the corelation id to notepad first and then copy the required text and then do a search on ULS.
Now , if you did copy the corelation id without that extra space, please ensure that you have sorted the ULS log files correctly according to the last modified date in the windows explorer. And then make a search on the sorted ULS files based on the time range.
A suggested way of exploring the ULS would be using the tool ULS Viewer , which can take inputs from multiple ULS log files and sort based on various columns like exception type, coorelation id ,etc.
Thirdly, from the nature of the problem that you posted it looks like checkout of a page causing this issue can have the scope of the root cause to the following :-
At any time there must be a masterpage or page layout not at approved or published state for the site where the page is located. This can cause a permission specific errors for the users when they try to access the site or this page. Please check that.
Ensure that there are no site quota locks that are reached while this file has been checkout.
Validate everything related to the health of the publishing infrastructure of sharepoint at the farm, web application and the site level.
All of the above are just pointers and not exact solution. If you can share the uls dump and corelation id messages we can assist you further.