Complex sentence: In a period of eight years (from 1980 to 1988) he revived the plants and turned them around into profit making businesses but in the mid-eighties the government guidelines changed and in 1988 the mills had to be shut down.
Split into simpler sentences: In a period of eight years (from 1980 to 1988) he revived the plants and turned them around into profit making businesses. In the mid-eighties the government guidelines changed and in 1988 the mills had to be shut down.