How does operators control and manipulate the prices of the stocks?

They use a technique called circular trading. A select group of people keep on buying and selling the stock among themselves and keep increasing the price.

When the general public notices that the stock price is increasing of that particular stock they start buying without checking the financials of the company. At that time the operators who have lot of stock sell only small quantities of stock and since demand is more and supply is less it increases the price further.

Once the stock price reaches a certain target set by the operators they start selling the stock and general public keeps on buying hoping it would go up further.

The operators make a huge return in relatively short period meanwhile the price crashes since there are no more buyers at the ridiculously inflated price and the general public then blames the stock market, SEBI, govt etc and says that the stock market is rigged