any cad softwares are not working on my pc? then what should I do?

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Hi Kanak,

Try starting with Tinkercad, which is a browser based CAD software and doesn't require you to download any software.

My co-worker JON-A-TRON does a great job of covering the basics of how to use Tinkercad in his Easy 3D Printing Class.

Hope this helps!

- Paige