Question

why had the Indian government put barrier on foreign trade and investment after independence

Answer 1

The Indian Government, after independance, had put barriers to foreign trade and foreign investment. This was considered necessary to protect the producers within the country from foreign competition.
Industries were just coming up in the 1950's and 1960's and competiton from imports would not have allowed many small scale industries to set up. Thus India allowed imports on very essential items such as machinery, petroleum etc.

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Answer 2

indian goverment put barriers because without that how development of india possible
Trade barriers help internal traders,businessmen for growth of indstries etc..
although it may be positive or negative.
Trade barriers like taxes on import,quota and tarrifs also help to keep BOP positive