Sorry, not been well AGAIN! Grrr, better now though.
Regarding the other problem which started after the above happened and @JorgeB and others have been very helpful but like above I never moved disks around. Just to jog your memory take a look at page 1 of this thread or just look at the quotes and photos asking why the disks had changed. I never changed the disk assignments at all so disk4 had no mountable filesystem. I never touched the assignments of the disks at all, I never changed them so I dont know how disk4 became changed but im the only one with access to Unraid here and it wasn't by mistake or anything.
Anyway, I decided that I would redownload all the disk4 data again as I know it's not recoverable. So to make disk4 work again it needs to be formatted, right?
Also
It not giving me the option to post or rerun xfs_repair on disk4. Disk2 lets me rerun it again if I want but not Disk4. I gather I still need to do xfs_repair on disk4? Disk2 is done now as I must have done it before disk4 as suggested by @trurl
There is a strange problem also. I cannot log in with any account from the webgui anymore? Root and the few other users are not recognised anymore? My usernames and Passwords are 100% correct as I can log in with them but only via the new Unraid Connect feature and all the usernames are now working along with their passwords but still will not let me login locally. What has caused this anyone?
So apart from Disk4 needs repairing still I think and the login problem what's next please?
Cheers