It will be really hard to pinpoint one reason. I am not political expert but based on common knowledge and what I have read there are few things I can think of:
1. Money played a big role.
2. Common people does not understand the complexities of finance.
3. One big thing in Punjab politics is pakke Akali or pakke Congrassi, that constitute about 20-25% of population for each party. It is almost impossible to get those votes. If we add up them it comes up to 40-50%. So to win, a new party or person has to get atleast 35% votes from the remaining 50%.
4. Needless to say Kabbadi worldcup played its own role. It helped Sukhbir Badal to strike a cord with common people especially from the villages.
5. Whether Manpreet Badal inadvertently palyed a role in Congress's defeat that I do not know.
I can think of these reasons and I may be off in my reasoning.
@J there were few of spelling miistakes in your question and also these elections were for legislative assembly (Vidhan Sabha) and not parliament (Lok Sabha).
yess very sad ki Manpreet Singh Badal ji nu public response nahin mileya... kujh ku gallan ne jo jimidaraan ne negative layian ne... even my own father...
1. they said ki eh tan aun ton pehla ee sabsidies khatam karan di gall karda
2. Manpreet Badal ne aunde ee zameeni kheti de bill 'ON' kar dene ne ...
3. Manpreet Badal da development da tarika vakhra hai... so Central response nahin milna te zameena de rate nahin vadhne..
4. karza lahun lai je sadi jeb vadhni ee hai te jo pehlan vadh rahe ne ohna ton ee kiun na vadhaayi jave...
eh te rahi mere apne ghar di story... baki andaza launa aukha vi koi nahin... As Arinder ji said... 'money plays big role'...
disappointed with Public response to MS Badal... hope he doesnt loose his heart and let this game stay on !!!