I'm pursuing Mechanical Engineering and i need to learn AUTOCAD, is there any site where i can download free video tutorials
If you are willing to pay monthly (first month free) then there are AutoCAD tutorials on LinkedIn Learning
If you don't have to use AutoCAD then Fusion360 is a very popular and equally capable programme that engineers and designers use and its free to use for startups and hobbyists and presumably students. As its cloud based the online support and comprehensive tutorials are all available online.
You can find many free courses if you search for it on YouTube.
Here is one example: AutoCad tutorials