Blank Content Pages for one account

Hi, I have many accounts on my CPanel / WHM VPS, where all accounts work well, while one of them has an issue when using CPanel of the account where some pages (such as Email Accounts) display blank content, where the header of the page exist and no errors appear in the source of the page "inspect elements", also that found in the wordpress website where everything work well but add and edit for page and post, where the same issue blank pages appear there, just for the same account, what I can do to find issue? .. It has appeared 3 days ago where everything was working well before that. Also the WHM home page appear without CSS where no errors in "inspect elements" of he browser Any log files or suggested thing to do ? Thank you. *Note: I use CloudFlare