Zain,
The PSpice and TINA-TI models are located in the product folder.
http://www.ti.com/product/LM5023
Simply scroll down to the models section. The models are encrypted can can only be used in PSpice version 15.7 or higher ot TINA-TI v9 (which is available for free download http://www.ti.com/tool/tina-ti ).
The LM5023 is also available in WEBENCH®. You can access it directly from the product folder as well.
Britt