How to get back Mental Ray plugin to my Render settings->Render using??? Please help

[vedtam]

Hi,
I am new to Maya.While I was doing some experiments with different lighting techniques after a few try Mental ray was not in the plugin list any more.I have reinstalled Maya but I still can’t render using Mental Ray! :(
Could someone tell me what am I doing wrong??

Thanx!

[hehud]

In Window-->Setting/Preferences-->PLug-in_Manager--> check the box "Mayatomr.mll"

if not there I don't know never happens to me ckecke the directory_Files

:)