Fix some issue on a joomla site

Hello,

I have a site on joomla 2.5
I have some issue that I want to fix.

1) I can not insert an embed video. I have insert the necessary plugin but when I enter the embed code it does not display anything.

2) When I am entering the site to offline mode I receive a 500 error


As I am using joomla for 9years I want someone to know about joomla and he can understand me.
I want to be fixed in 24hours from the time that we start this project.



Thanks for reading