What ll be the best strategy for winning back lost customers?

The answer would be at CRC & PR departments...

will, you should first know the reason behind leaving you or switching to competitors, after that you have to know their needs and wants and offer them what satisfy them with a unique or new way, you can also offer them discounts or offers that will motivate them to buy your product, or get them back to use your service.

Customer relationships plays a vital role for the success of any business. So we need to develop business strategy for the customer retention. Some of the factors required for customer retention includes: Customer loyalty, Added value services, Quality products & services, After sales services, Good rapport with the customers and Trust. So if we implement these few factors consistently we can retain the customer loyalty and good strategy for winning the hearts and minds of the lost customers.

The best action plan for win back strategy is as follow

1-distinguish the cause of customer attriation

2-interacting with the customer again

3-develope new locality brogrammes

4-create institutional tie which will attract the customer to work with you again

5-be swift and sincere

One of the good management practices in sales management is the "loss analysis process" which is either missing, taken lightly or carelessly, or faked out to fit the internal politics within the sales organization.  If this practice is insisted on as a "must" in every loss situation, regardless how unpleasant, embarrassing, or time/effort consuming it may take,  facts will start emerging in front of our eyes regarding we are losing byusiness and why customers go to our competition.  Furthermore, this process needs to be practiced correctly, precisely, bluntly and with total honesty.  in order to see valid results/conclusions, and in order to see remedy actions taking their effect in minimizing such losses in the future and to win as many of these lost customers as possible. 

Desgining the "loss analysis report" to be used in this process and what it should include (content) and who should fill it, who should review it, who should draw conclusions from it, and who should act on it ..... etc...etc.   need to be taken into account with top/senior management, business owners and the sales organization itself. 

public relations

You can't answer this question until you find out the reason for them leaving you in the first place. Conduct customer satisfaction research first! You Customer Retention strategy should tackle or undo these reasons. It could anything from reasons related to your own offering and company (image, product, price, positioning etc.) to external factors (economic, market, competition, customer habits).

Once we lost customer its very difficult to re-alliegn.

It requires the investment of time again, CRC & PR, offering something extra, to reorganize the whole picture again to make him see that, even dispute, you are the best option, and patience to the height of sky level.

Although there are tons of books and theories, but in practical they do not work, as tought. 

The above mentioned steps have been tested by myself in pracitcal.