With my little knowledge in R (m new in R programming), I read somewhere that if you are using readOGR() function do not add file extension. Yes the ESRI shapefile has .shp extension...
After reading you, I added .shp (I thinks that's what you want to say), but the problem persists.
Cpde:
trainData <- readOGR("C:/Users/Zainab Khan/Desktop/india/train.shp", "polygons")
Error Message:
Error in ogrInfo(dsn = dsn, layer = layer, encoding = encoding, use_iconv = use_iconv, :
Cannot open data source