Recently Google disapproved some of my ads in Google Adwords with the following reason:

"Working Back Button
Links to your website must allow users to enter and exit the landing page easily, and to return to the Google search results page or ad network by clicking once on the browser's 'Back' button. "

I don't understand because I tried myself and when I click on the back button i return to Google Search. Also all my ads link to the homapge but only 5 of them have been disapproved!!

Has anybody experienced this before or know how i can fix this?

Unless you are running some javascript to disable back button, this should not apply to you. Check your website and see if there is any flashy js.

Alternatively, are you redirecting from the landing page? Or do you have popups or popunders? These will sometimes get the same message that you've seen.