The requested URL /Work1/a.php was not found on this server.

please how do i fix this The requested URL /Work1/a.php was not found on this server.

not enough information

not enough information

Thats the only information i have....i cant acess my site contents it keeps saying error 404 file not found

Let's try this again.

The more information you can provide, the more someone can help you.
1)  What setup are you running.  Apache, NGINX+ Apache, ...  ***CWP -> Webserver Settings -> Select Webserver **
2)  If you don't mine, post the domain your having trouble with.
3)  check your error log, and possibly post the last 30 lines or so right after you try to hit the page.  Of course this error log will depend on #1.