Also, make sure that you are using the latest version of your Web browser.
Sometimes firewalls or anti-virus programs will block access to editing functions. This can especially occur in corporate or academic networks. Unrestricted access to gstatic.com is necessary.
Ad Blockers and Pop-up Blockers can prevent the use of parts of Google Sites.
Users are reporting that the Diigo Web Collector Extension prevents them from editing their sites.
Setting your zoom level to anything other than 100% can also be a problem.
If you have moved from a Google Sites personal account to an Apps account and have lost access please read Steegle's information:
If a particular page redirects to another site before you can click to edit it try pressing the escape key on your keyboard immediately when you access the page, or as soon as the page opens hit the key m and then g then r. This will open the revision page. Revert an earlier version.
You can also go to Pages > List page by adding /system/app/pages/admin/pagelisting to the end of your site URL. Find the affected page and click on the revision number (in the Revisions column) Go back through the revision history to find the last save without the error and revert to that version.
If your computer locks up or your browser freezes when you try to edit your site:
For other suggestions please read:My Computer hangs (locks up)/web browser freezes (site frozen) at "Recovering edit from draft" - why?
If you still can't edit your site Go to the Google Sites Help Forum and post a question explaining you can no longer edit your site and make sure you provide the URL (web address) of your site.
A. Revert to an earlier version
B. Remove the page
If a page has been designated a landing page you wont be able to delete it. You must first make a different page the landing page.
If the Analytics code won't save when pasting it in, try entering the code character by character instead of pasting it.
This happens when you upload the background image with spaces in the file name so if your file name is site header background.png change it to site-header-background.png and this will stop happening.
There is a bug in the editing function when there are some large custom logos. Clicking on the header actually clicks on the logo, which causes a page redirect. A fix is in the works but in the meantime the workaround is to click the upper left corner of the header, as this should hit the overlay element and not the logo itself.