Change in Extension of Index Page(.htm from .html)

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Hi every one there!
I have replaced my home page(earlier the extension was .html and now it
is .htm). Google had indexed the .html page .The robots crawled the
home page  last on 17th June and since then the cache is not showing
any updates. Is changing the extension of home page harmful and the
main reason whyy google is not indexing other pages of my site. What
should i do?
my site is-

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