Unable to change price or quantity internal error

[ismtech]

Hello

Thanks for taking time to read this.

I am not able to change the quantity or price on any products even the ones that are preinstalled with prestashop installing , for some reason I go to catalog click the quantity box and get this error

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, webmaster@mydomain and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

Please can anyone help or provide any advice.

Kind Regards