Is this a brand new installation of Rhino 4, a brand new installation of Windows 8, or both? Upgrades of either or both?
Or is this a setup you’ve been using for some time and now [quote=“deepakp017, post:1, topic:29112”]
suddenly all the import & export plugins are missing also some commands like untrimme seems unknown to Rhino !!
[/quote] ?
One thing that is worth noting: Windows 8 was never considered very good, and was quickly supplanted by 8.1, which I suggest you do on general principles.
Any advice about your concern will depend on your answers to the above questions.