I downloaded sra-toolkit from sra website for 64bit Windows.
After extracting I tested it from bin folder:
sra-toolkit\bin> fastq-dump --stdout -X 2 SRR390728
but it throws error:
2015-12-15T09:54:40 fastq-dump.2.5.5 err: item not found while constructing within virtual database module - the path 'SRR390728' cannot be opened as database or table
what may be the cause and how to get it working.