I am having GC for USA and staying india since 7 month. Am I allowed to work forus company even though I amin india since more than 7 month.

Secondly if I convert to tourist visa then am I still allowed to work for us company from india.

Everything depends on the category of US visa. Tourist visa is no good for employment. If you get a job in US company branch in India they will procure the necessary document from USA so that US embassy in India can give you the permission to stay and work in the US branch of the US company